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2018 |
Jenny A. Nij Bijvank; A. Petzold; L. J. Balk; H. S. Tan; Bernard M. J. Uitdehaag; M. Theodorou; L. J. Rijn A standardized protocol for quantification of saccadic eye movements: DEMoNS Journal Article In: PLoS ONE, vol. 13, no. 7, pp. e0200695, 2018. @article{NijBijvank2018, OBJECTIVE: Quantitative saccadic testing is a non-invasive method of evaluating the neural networks involved in the control of eye movements. The aim of this study is to provide a standardized and reproducible protocol for infrared oculography measurements of eye movements and analysis, which can be applied for various diseases in a multicenter setting. METHODS: Development of a protocol to Demonstrate Eye Movement Networks with Saccades (DEMoNS) using infrared oculography. Automated analysis methods were used to calculate parameters describing the characteristics of the saccadic eye movements. The two measurements of the subjects were compared with descriptive and reproducibility statistics. RESULTS: Infrared oculography measurements of all subjects were performed using the DEMoNS protocol and various saccadic parameters were calculated automatically from 28 subjects. Saccadic parameters such as: peak velocity, latency and saccade pair ratios showed excellent reproducibility (intra-class correlation coefficients > 0.9). Parameters describing performance of more complex tasks showed moderate to good reproducibility (intra-class correlation coefficients 0.63-0.78). CONCLUSIONS: This study provides a standardized and transparent protocol for measuring and analyzing saccadic eye movements in a multicenter setting. The DEMoNS protocol details outcome measures for treatment trial which are of excellent reproducibility. The DEMoNS protocol can be applied to the study of saccadic eye movements in various neurodegenerative and motor diseases. |
Julie Ouerfelli-Ethier; Basma Elsaeid; Julie Desgroseilliers; Douglas P. Munoz; Gunnar Blohm; Aarlenne Zein Khan Anti-saccades predict cognitive functions in older adults and patients with Parkinson's disease Journal Article In: PLoS ONE, vol. 13, no. 11, pp. e0207589, 2018. @article{OuerfelliEthier2018, A major component of cognitive control is the ability to act flexibly in the environment by either behaving automatically or inhibiting an automatic behaviour. The interleaved pro/anti-saccade task measures cognitive control because the task relies on one's abilities to switch flexibly between pro and anti-saccades, and inhibit automatic saccades during anti-saccade trials. Decline in cognitive control occurs during aging or neurological illnesses such as Parkinson's disease (PD), and indicates decline in other cognitive abilities, such as memory. However, little is known about the relationship between cognitive control and other cognitive processes. Here we investigated whether anti-saccade performance can predict decision-making, visual memory, and pop-out and serial visual search performance. We tested 34 younger adults, 22 older adults, and 20 PD patients on four tasks: an interleaved pro/anti-saccade, a spatial visual memory, a decision-making and two types of visual search (pop-out and serial) tasks. Anti-saccade performance was a good predictor of decision-making and visual memory abilities for both older adults and PD patients, while it predicted visual search performance to a larger extent in PD patients. Our results thus demonstrate the suitability of the interleaved pro/anti-saccade task as a cognitive marker of cognitive control in aging and PD populations. |
Sara Ajina; Holly Bridge Blindsight relies on a functional connection between hMT+ and the lateral geniculate nucleus, not the pulvinar Journal Article In: PLoS Biology, vol. 16, no. 7, pp. e2005769, 2018. @article{Ajina2018, When the primary visual cortex (V1) is damaged, the principal visual pathway is lost, causing a loss of vision in the opposite visual field. While conscious vision is impaired, patients can still respond to certain images; this is known as ‘blindsight'. Recently, a direct anatomical connection between the lateral geniculate nucleus (LGN) and human motion area hMT+ has been implicated in blindsight. However, a functional connection between these structures has not been demonstrated. We quantified functional MRI responses to motion in 14 patients with unilateral V1 damage (with and without blindsight). Patients with blindsight showed significant activity and a preserved sensitivity to speed in motion area hMT+, which was absent in patients without blindsight. We then compared functional connectivity between motion area hMT+ and a number of structures implicated in blindsight, including the ventral pulvinar. Only patients with blindsight showed an intact functional connection with the LGN but not the other structures, supporting a specific functional role for the LGN in blindsight. |
Daniel S. Asfaw; Pete R. Jones; M. M. Vera; Nicholas D. Smith; David P. Crabb Does glaucoma alter eye movements when viewing images of natural scenes ? A between-eye study Journal Article In: Investigative Ophthalmology & Visual Science, vol. 59, no. 8, pp. 3189–3198, 2018. @article{Asfaw2018a, PURPOSE. To investigate whether glaucoma produces measurable changes in eye movements. METHODS. Fifteen glaucoma patients with asymmetric vision loss (difference in mean deviation [MD] > 6 dB between eyes) were asked to monocularly view 120 images of natural scenes, presented sequentially on a computer monitor. Each image was viewed twice—once each with the better and worse eye. Patients' eye movements were recorded with an Eyelink 1000 eye-tracker. Eye-movement parameters were computed and compared within participants (better eye versus worse eye). These parameters included a novel measure: saccadic reversal rate (SRR), as well as more traditional metrics such as saccade amplitude, fixation counts, fixation duration, and spread of fixation locations (bivariate contour ellipse area [BCEA]). In addition, the associations of these parameters with clinical measures of vision were investigated. RESULTS. In the worse eye, saccade amplitude (p = 0.012; -13%) and BCEA (p = 0.005; -16 %) were smaller, while SRR was greater (p = 0.018; +16%). There was a significant correlation between the intereye difference in BCEA, and differences in MD values (Spearman's r = 0.65; p = 0.01), while differences in SRR were associated with differences in visual acuity (Spearman's r = 0.64; p = 0.01). Furthermore, between-eye differences in BCEA were a significant predictor of between-eye differences in MD: for every 1-dB difference in MD, BCEA reduced by 6.2% (95% confidence interval, 1.6%–10.3%). CONCLUSIONS. Eye movements are altered by visual field loss, and these changes are related to changes in clinical measures. Eye movements recorded while passively viewing images could potentially be used as biomarkers for visual field damage. |
Sabrina Baldofski; Patrick Lüthold; Ingmar Sperling; Anja Hilbert Visual attention to pictorial food stimuli in individuals with night eating syndrome: an eye-tracking study Journal Article In: Behavior Therapy, vol. 49, no. 2, pp. 262–272, 2018. @article{Baldofski2018, Night eating syndrome (NES) is characterized by excessive evening and/or nocturnal eating episodes. Studies indicate an attentional bias towards food in other eating disorders. For NES, however, evidence of attentional food processing is lacking. Attention towards food and non-food stimuli was compared using eye-tracking in 19 participants with NES and 19 matched controls without eating disorders during a free exploration paradigm and a visual search task. In the free exploration paradigm, groups did not differ in initial fixation position or gaze duration. However, a significant orienting bias to food compared to non-food was found within the NES group, but not in controls. A significant attentional maintenance bias to non-food compared to food was found in both groups. Detection times did not differ between groups in the search task. Only in NES, attention to and faster detection of non-food stimuli were related to higher BMI and more evening eating episodes. The results might indicate an attentional approach-avoidance pattern towards food in NES. However, further studies should clarify the implications of attentional mechanisms for the etiology and maintenance of NES. |
T. Balsdon; Richard Schweitzer; Tamara L. Watson; Martin Rolfs All is not lost: Post-saccadic contributions to the perceptual omission of intra-saccadic streaks Journal Article In: Consciousness and Cognition, vol. 64, pp. 19–31, 2018. @article{Balsdon2018, Saccades rapidly jerk the eye into new positions, yet we rarely experience the motion streaks imposed on the retinal image. Here we examined spatial and temporal properties of post-saccadic masking—one potential explanation of this perceptual omission. Observers judged the motion direction of a target stimulus, a Gaussian blob, that moved vertically upwards or downwards and then back to its initial position, just as observers made a saccade. We manipulated the onset and offset of the target and of distractors in various spatial relations to the target, and assessed their effect on performance and subjective confidence. Although the presence of the target after the saccade caused the strongest omission, the offset of spatially distant distractor stimuli upon saccade offset also impaired performance. The temporal properties of these two separate effects suggest that, in addition to masking, an independent effect of attentional distraction further accentuates perceptual omission of intra-saccadic motion streaks. |
Chiara Banfi; Ferenc Kemény; Melanie Gangl; Gerd Schulte-Körne; Kristina Moll; Karin Landerl Visual attention span performance in German-speaking children with differential reading and spelling profiles: No evidence of group differences Journal Article In: PLoS ONE, vol. 13, no. 6, pp. e0198903, 2018. @article{Banfi2018, An impairment in the visual attention span (VAS) has been suggested to hamper reading performance of individuals with dyslexia. It is not clear, however, if the very nature of the deficit is visual or verbal and, importantly, if it affects spelling skills as well. The current study investigated VAS by means of forced choice tasks with letters and symbols in a sample of third and fourth graders with age-adequate reading and spelling skills (n= 43), a typical dyslexia profile with combined reading and spelling deficits (n= 26) and isolated spelling deficits (n= 32). The task was devised to contain low phonological short-term memory load and to overcome the limitations of oral reports. Notably, eye-movements were monitored to control that children fixated the center of the display when stimuli were presented. Results yielded no main effect of group as well as no group-related interactions, thus showing that children with dyslexia and isolated spelling deficits did not manifest a VAS deficit for letters or symbols once certain methodological aspects were controlled for. The present results could not replicate previous evidence for the involvement of VAS in reading and dyslexia. |
Bengi Baran; David Correll; Tessa C. Vuper; Alexandra Morgan; Simon J. Durrant; Dara S. Manoach; Robert Stickgold Spared and impaired sleep-dependent memory consolidation in schizophrenia Journal Article In: Schizophrenia Research, vol. 199, pp. 83–89, 2018. @article{Baran2018, Objective: Cognitive deficits in schizophrenia are the strongest predictor of disability and effective treatment is lacking. This reflects our limited mechanistic understanding and consequent lack of treatment targets. In schizophrenia, impaired sleep-dependent memory consolidation correlates with reduced sleep spindle activity, suggesting sleep spindles as a potentially treatable mechanism. In the present study we investigated whether sleep-dependent memory consolidation deficits in schizophrenia are selective. Methods: Schizophrenia patients and healthy individuals performed three tasks that have been shownto undergo sleep-dependent consolidation: the Word Pair Task (verbal declarative memory), the Visual Discrimination Task (visuoperceptual procedural memory), and the Tone Task (statistical learning). Memory consolidation was tested 24 h later, after a night of sleep. Results: Compared with controls, schizophrenia patients showed reduced overnight consolidation ofword pair learning. In contrast, both groups showed similar significant overnight consolidation of visuoperceptual procedural memory. Neither group showed overnight consolidation of statistical learning. Conclusion: The present findings extend the known deficits in sleep-dependent memory consolidation in schizophrenia to verbal declarative memory, a core, disabling cognitive deficit. In contrast, visuoperceptual procedural memorywas spared. These findings support the hypothesis that sleep-dependent memory consolidation deficits in schizophrenia are selective, possibly limited to tasks that rely on spindles. These findings reinforce the importance ofdeficient sleep-dependent memory consolidation among the cognitive deficits ofschizophrenia and suggest sleep physiology as a potentially treatable mechanism. |
Jeffrey S. Bedwell; Christopher C. Spencer; Chi C. Chan; Pamela D. Butler; Pejman Sehatpour; Joseph Schmidt The P1 visual-evoked potential, red light, and transdiagnostic psychiatric symptoms Journal Article In: Brain Research, vol. 1687, pp. 144–154, 2018. @article{Bedwell2018, A reduced P1 visual-evoked potential amplitude has been reported across several psychiatric disorders, including schizophrenia-spectrum, bipolar, and depressive disorders. In addition, a difference in P1 amplitude change to a red background compared to its opponent color, green, has been found in schizophrenia-spectrum samples. The current study examined whether specific psychiatric symptoms that related to these P1 abnormalities in earlier studies would be replicated when using a broad transdiagnostic sample. The final sample consisted of 135 participants: 26 with bipolar disorders, 25 with schizophrenia-spectrum disorders, 19 with unipolar depression, 62 with no current psychiatric disorder, and 3 with disorders in other categories. Low (8%) and high (64%) contrast check arrays were presented on gray, green, and red background conditions during electroencephalogram, while an eye tracker monitored visual fixation on the stimuli. Linear regressions across the entire sample (N = 135) found that greater severity of both clinician-rated and self-reported delusions/magical thinking correlated with a reduced P1 amplitude on the low contrast gray (neutral) background condition. In addition, across the entire sample, higher self-reported constricted affect was associated with a larger decrease in P1 amplitude (averaged across contrast conditions) to the red, compared to green, background. All relationships remained statistically significant after covarying for diagnostic class, suggesting that they are relatively transdiagnostic in nature. These findings indicate that early visual processing abnormalities may be more directly related to specific transdiagnostic symptoms such as delusions and constricted affect rather than specific psychiatric diagnoses or broad symptom factor scales. |
Nathalie N. Bélanger; Michelle Lee; Elizabeth R. Schotter Young skilled deaf readers have an enhanced perceptual span in reading Journal Article In: Quarterly Journal of Experimental Psychology, vol. 71, no. 1, pp. 291–301, 2018. @article{Belanger2018, Recent evidence suggests that deaf people have enhanced visual attention to simple stimuli in the parafovea in comparison to hearing people. Although a large part of reading involves processing the fixated words in foveal vision, readers also utilize information in parafoveal vision to pre-process upcoming words and decide where to look next. We investigated whether auditory deprivation affects low-level visual processing during reading, and compared the perceptual span of deaf signers who were skilled and less skilled readers to that of skilled hearing readers. Compared to hearing readers, deaf readers had a larger perceptual span than would be expected by their reading ability. These results provide the first evidence that deaf readers' enhanced attentional allocation to the parafovea is used during a complex cognitive task such as reading. |
Francisco M. Costela; Daniel R. Saunders; Sidika Kajtezovic; Dylan J. Rose; Russell L. Woods Measuring the difficulty watching video with hemianopia and an initial test of a rehabilitation approach Journal Article In: Translational Vision Science & Technology, vol. 7, no. 4, pp. 1–10, 2018. @article{Costela2018, Purpose: If you cannot follow the story when watching a video, then the viewing experience is degraded. We measured the difficulty of following the story, defined as the ability to acquire visual information, which is experienced by people with homonymous hemianopia (HH). Further, we proposed and tested a novel rehabilitation aid. Methods: Participants watched 30-second directed video clips. Following each video clip, subjects described the visual content of the clip. An objective score of information acquisition (IA) was derived by comparing each new response to a control database of descriptions of the same clip using natural language processing. Study 1 compared 60 participants with normal vision (NV) to 24 participants with HH to test the hypothesis that participants with HH would score lower than NV participants, consistent with reports from people with HH that describe difficulties in video watching. In the second study, 21 participants with HH viewed clips with or without a superimposed dynamic cue that we called a content guide. We hypothesized that IA scores would increase using this content guide. Results: The HH group had a significantly lower IA score, with an average of 2.8, compared with 4.3 shared words of the NV group (mixed-effects regression, P < 0.001). Presence of the content guide significantly increased the IA score by 0.5 shared words (P = 0.03). Conclusions: Participants with HH had more difficulty acquiring information from a video, which was objectively demonstrated (reduced IA score). The content guide improved information acquisition, but not to the level of people with NV. Translational Relevance: The value as a possible rehabilitation aid of the content guide warrants further study that involves an extended period of content-guide use and a randomized controlled trial. |
A. Cucca; I. Acosta; M. Berberian; A. C. Lemen; John-Ross Rizzo; M. Felice Ghilardi; Angelo Quartarone; A. S. Feigin; A. Di Rocco; M. C. Biagioni Visuospatial exploration and art therapy intervention in patients with Parkinson's disease: An exploratory therapeutic protocol Journal Article In: Complementary Therapies in Medicine, vol. 40, pp. 70–76, 2018. @article{Cucca2018, Though abnormalities of visuospatial function occur in Parkinson's disease, the impact of such deficits on functional independence and psychological wellbeing has been historically under-recognized, and effective treatments for this impairment are unknown. These symptoms can be encountered at any stage of the disease, affecting many activities of daily living, and negatively influencing mood, self-efficacy, independence, and overall quality of life. Furthermore, visuospatial dysfunction has been recently linked to gait impairment and falls, symptoms that are known to be poor prognostic factors. Here, we aim to present an original modality of neurorehabilitation designed to address visuospatial dysfunction and related symptoms in Parkinson's disease, known as “Art Therapy”. Art creation relies on sophisticated neurologic mechanisms including shape recognition, motion perception, sensory-motor integration, abstraction, and eye-hand coordination. Furthermore, art therapy may enable subjects with disability to understand their emotions and express them through artistic creation and creative thinking, thus promoting self-awareness, relaxation, confidence and self-efficacy. The potential impact of this intervention on visuospatial dysfunction will be assessed by means of combined clinical, behavioral, gait kinematic, neuroimaging and eye tracking analyses. Potential favorable outcomes may drive further trials validating this novel paradigm of neurorehabilitation. |
Fabian J. David; Lisa C. Goelz; Ruth Z. Tangonan; Leonard Verhagen Metman; Daniel M. Corcos Bilateral deep brain stimulation of the subthalamic nucleus increases pointing error during memory-guided sequential reaching Journal Article In: Experimental Brain Research, vol. 236, no. 4, pp. 1053–1065, 2018. @article{David2018, Deep brain stimulation of the subthalamic nucleus (STN DBS) significantly improves clinical motor symptoms, as well as intensive aspects of movement like velocity and amplitude in patients with Parkinson's disease (PD). However, the effects of bilateral STN DBS on integrative and coordinative aspects of motor control are equivocal. The aim of this study was to investigate the effects of bilateral STN DBS on integrative and coordinative aspects of movement using a memory-guided sequential reaching task. The primary outcomes were eye and finger velocity and end-point error. We expected that bilateral STN DBS would increase reaching velocity. More importantly, we hypothesized that bilateral STN DBS would increase eye and finger end-point error and this would not simply be the result of a speed accuracy trade-off. Ten patients with PD and bilaterally implanted subthalamic stimulators performed a memory-guided sequential reaching task under four stimulator conditions (DBS-OFF, DBS-LEFT, DBS-RIGHT, and DBS-BILATERAL) over 4 days. DBS-BILATERAL significantly increased eye velocity compared to DBS-OFF, DBS-LEFT, and DBS-RIGHT. It also increased finger velocity compared to DBS-OFF and DBS-RIGHT. DBS-BILATERAL did not change eye end-point error. The novel finding was that DBS-BILATERAL increased finger end-point error compared to DBS-OFF, DBS-LEFT, and DBS-RIGHT even after adjusting for differences in velocity. We conclude that bilateral STN DBS may facilitate basal ganglia–cortical networks that underlie intensive aspects of movement like velocity, but it may disrupt selective basal ganglia–cortical networks that underlie certain integrative and coordinative aspects of movement such as spatial accuracy. |
Bertrand Degos; Ilhame Ameqrane; Sophie Rivaud-Péchoux; Pierre Pouget; Marcus Missal Short-term temporal memory in idiopathic and Parkin-associated Parkinson's disease Journal Article In: Scientific Reports, vol. 8, pp. 7637, 2018. @article{Degos2018, In a rapidly changing environment, we often know when to do something before we have to do it. This preparation in the temporal domain is based on a ‘perception' of elapsed time and short-term memory of previous stimulation in a similar context. These functions could be perturbed in Parkinson's disease. Therefore, we investigated their role in eye movement preparation in sporadic Parkinson's disease and in a very infrequent variant affecting the Parkin gene. We used a simple oculomotor task where subjects had to orient to a visual target and movement latency was measured. We found that in spite of an increased average reaction time, the influence of elapsed time on movement preparation was similar in controls and the two groups of PD patients. However, short-term temporal memory of previous stimulation was severely affected in sporadic PD patients either ON or OFF dopaminergic therapy. We conclude that the two different contributions to temporal preparation could be dissociated. Moreover, a short-term temporal memory deficit might underlie temporal cognition deficits previously observed in PD. |
Louis F. Dell'Osso; Richard W. Hertle; Jonathan B. Jacobs Clinical and ocular motor complications of extraocular muscle extirpation for infantile nystagmus syndrome Journal Article In: Journal of AAPOS, vol. 22, no. 2, pp. 110–114, 2018. @article{DellOsso2018, Purpose: To describe the effects of extraocular muscle extirpation performed after previous eye muscle surgery in a 20-year-old woman with infantile nystagmus syndrome (INS) for whom we have 19 years of follow-up data. Methods: Clinical examinations were performed. Eye movement data analysis was carried out using the eXpanded Nystagmus Acuity Function (NAFX) and longest foveation domain (LFD). Results: The patient re-presented to the authors at age 20, 2 years after bilateral anterior myectomy of the horizontal rectus muscles, bilateral anterior nasal transposition of the inferior oblique muscle, and bilateral superior oblique recessions. Evaluation revealed deterioration in nystagmus at lateral gaze angles, new incomitant strabismus with severe loss of convergence, limited ductions, saccadic hypometria, slow saccades, and hypo-accommodation. Also, there was a pre- to post-extirpation minimal change of 21% in her peak NAFX, a 50% decrease in LFD, plus a predominant, asymmetric, multiplanar oscillation. Conclusions: It appears that in this patient, horizontal extirpation failed to abolish the nystagmus and caused significant, new, symptomatic deficits interfering with many of the patient's visual functions. |
Joris A. Elshout; Douwe P. Bergsma; Jacqueline Sibbel; Annette Baars-Elsinga; Paula Lubbers; Freekje Van Asten; Johanna Visser-Meily; Albert V. Van Den Berg Improvement in activities of daily living after visual training in patients with homonymous visual field defects using Goal Attainment Scaling Journal Article In: Restorative Neurology and Neuroscience, vol. 36, no. 1, pp. 1–12, 2018. @article{Elshout2018, BACKGROUND: Stroke is the most common cause of homonymous visual field defects (HVFDs). Yet, there is no standard protocol for composing a rehabilitation program. OBJECTIVE: In this study we assess ADL gain of visual training for vision restoration in HVFD patients by means of Goal Attainment Scaling. METHODS: Thirty-five patients trained two predefined regions of the visual field successively at home. In each region we compared the effects of both training rounds, one of which was thus 'directed' and the other 'undirected'. Visual fields were measured with Humphrey and Goldmann perimetry. QoL was assessed with three stroke-related questionnaires and ADL with Goal Attainment Scaling (GAS). RESULTS: Visual training improved the visual field for both Goldmann (ECSG = 5.82+/-0.94 mm; p = <0.001; n = 31) and Humphrey (0.79+/-0.20 dB; p = <0.001; n = 28) perimetry. All standardized stroke questionnaires were significantly improved after training (p < 0.039; n = 29), but showed no significant relation with either type of field improvement (p > 0.359). About 75% of the patients improved on their (personalized) GAS score. Interestingly, after both training rounds the GAS score increased in proportion to the extent of visual field improvement, for Goldmann border shift (p = 0.042; r = 0.38; n = 29) but not for Humphrey sensitivity increase (p = 0.337; r = 0.192; n = 28). Multiple regression revealed that GAS score was linearly related to the directed training component for Humphrey perimetry, but not for undirected training. CONCLUSION: Together these data suggest that (1) visual training aimed at vision restoration leads to visual field improvement and (2) the extent of visual field improvement is linearly related to the improvement of personal activities of daily living as evaluated by means of GAS. In conclusion, a personalized evaluation to assess treatment success showed the clinical significance of a visual training for vision restoration. |
Joan Esse Wilson; Michael C. Trumbo; J. Kevin Wilson; Claudia D. Tesche In: Journal of Neural Transmission, vol. 125, no. 12, pp. 1857–1866, 2018. @article{EsseWilson2018, Social deficits are core to autism spectrum disorder (ASD). Current treatments are extremely time- and labor-intensive. Transcranial direct current stimulation (tDCS) may be a promising treatment modality to safely enhance treatments targeting social cognition and social skills. This pilot study investigates the effectiveness of social skills treatment interventions paired with anodal tDCS for six adults 18-58 years with ASD. Differences were predicted on the verbal fluency (VF) test and a test of social skills (TASSK-M) for verum (2.0 mA) vs. sham tDCS, which was randomly assigned in a within-subjects, double-blinded design in adults with ASD with normal or higher cognitive functioning. The anode electrode was placed over right temporoparietal (CP6) and cathode over ipsilateral deltoid. Wilcoxon signed-rank tests for paired data indicated that participants received a significantly higher score on the VF test after receiving verum tDCS compared to sham tDCS, with no significant differences found on the TASSK-M. Post-hoc analysis showed that the emotion-word portion of the VF test, specifically, indicated significant differences when comparing verum to sham tDCS conditions. These findings provide optimism for the use of tDCS as delivered in the current study paired with social skills treatment interventions for ASD, particularly for improving skills of emotion verbal fluency. |
Kris Evers; Goedele Van Belle; Jean Steyaert; Ilse Noens; Johan Wagemans Gaze-contingent display changes as new window on analytical and holistic face perception in children with Autism Spectrum Disorder Journal Article In: Child Development, vol. 89, no. 2, pp. 430–445, 2018. @article{Evers2018, The strength of holistic face perception in children with autism spectrum disorder (ASD) was evaluated byapplying the gaze-contingent mask and window technique to a face matching and discrimination task in 6- to14-year-old children with (n = 36) and without ASD (n = 47), and by examining fixation patterns. Behavioralresults suggested a slower and less efficient face processing in the ASD sample compared with the matchedcontrol group. Comparing the moving mask and window conditions revealed a reduced holistic face process-ing bias in the younger age group but not in the older sample. Preferential viewing patterns revealed bothsimilarities and differences between both participant groups. |
Gerardo Fernández; David Orozco; Osvaldo Agamennoni; Marcela Schumacher; Silvana Sañudo; Juan Biondi; Mario A. Parra Visual processing during short-term memory binding in mild Alzheimer's disease Journal Article In: Journal of Alzheimer's Disease, vol. 63, no. 1, pp. 185–194, 2018. @article{Fernandez2018a, Patients with Alzheimer disease (AD) typically present with attentional and oculomotor abnormalities that can have an impact on visual processing and associated cognitive functions. Over the last few years, we have witnessed a shift towards the analyses of eye movement behaviors as a means to further our understanding of the pathophysiology of common disorders such as AD. However, little work has been done to unveil the link between eye moment abnormalities and poor performance on cognitive tasks known to be markers for AD patients, such as the short-term memory-binding task. This was the aim of the present study. We analyzed eye movement fixation behaviors of thirteen healthy older adults (Controls) and thirteen patients with probable mild AD while they performed the visual short-term memory binding task (Parra et al., 2011). The short-term memory binding task asks participants to detect changes across two consecutive arrays of two bicolored object whose features (i.e., colors) have to be remembered separately (i.e., Unbound Colors), or combined within integrated objects (i.e., Bound Colors). Patients with mild AD showed the well-known pattern of selective memory binding impairments. This was accompanied by significant impairments in their eye movements only when they processed Bound Colors. Patients with mild AD remarkably decreased their mean gaze duration during the encoding of color-color bindings. These findings open new windows of research into the pathophysiological mechanisms of memory deficits in AD patients and the link between its phenotypic expressions (i.e., oculomotor and cognitive disorders). We discuss these findings considering current trends regarding clinical assessment, neural correlates, and potential avenues for robust biomarkers. |
Denis Pélisson; Ouazna Habchi; Muriel T. N. Panouillères; Charles Hernoux; Alessandro Farnè A cortical substrate for the long-term memory of saccadic eye movements calibration Journal Article In: NeuroImage, vol. 179, pp. 348–356, 2018. @article{Pelisson2018, How movements are continuously adapted to physiological and environmental changes is a fundamental question in systems neuroscience. While many studies have elucidated the mechanisms which underlie short-term sensorimotor adaptation (∼10–30 min), how these motor memories are maintained over longer-term (>3–5 days) -and thanks to which neural systems-is virtually unknown. Here, we examine in healthy human participants whether the temporo-parietal junction (TPJ) is causally involved in the induction and/or the retention of saccadic eye movements' adaptation. Single-pulse transcranial magnetic stimulation (spTMS) was applied while subjects performed a ∼15min size-decrease adaptation task of leftward reactive saccades. A TMS pulse was delivered over the TPJ in the right hemisphere (rTPJ) in each trial either 30, 60, 90 or 120 msec (in 4 separate adaptation sessions) after the saccade onset. In two control groups of subjects, the same adaptation procedure was achieved either alone (No-TMS) or combined with spTMS applied over the vertex (SHAM-TMS). While the timing of spTMS over the rTPJ did not significantly affect the speed and immediate after-effect of adaptation, we found that the amount of adaptation retention measured 10 days later was markedly larger (42%) than in both the No-TMS (21%) and the SHAM-TMS (11%) control groups. These results demonstrate for the first time that the cerebral cortex is causally involved in maintaining long-term oculomotor memories. |
Christian H. Poth; Werner X. Schneider Attentional competition across saccadic eye movements Journal Article In: Acta Psychologica, vol. 190, pp. 27–37, 2018. @article{Poth2018, Human behavior is guided by visual object recognition. For being recognized, objects compete for limited attentional processing resources. The more objects compete, the lower is performance in recognizing each individual object. Here, we ask whether this competition is confined to eye fixations, periods of relatively stable gaze, or whether it extends from one fixation to the next, across saccadic eye movements. Participants made saccades to a peripheral saccade target. After the saccade, a letter was briefly presented within the saccade target and terminated by a mask. Object recognition of the letter was assessed as participants' report. Critically, either no, two, or four additional non-target objects appeared before the saccade. In Experiment 1, presaccadic non-targets were task-irrelevant and had no effects on postsaccadic object recognition. In Experiment 2, presaccadic non-targets were task-relevant and, here, postsaccadic object recognition deteriorated with increasing number of presaccadic non-targets. As suggested by Experiment 3 and a mathematical model, this effect was due to a slowing down but also a delayed start of visual processing after the saccade. Together, our findings show that objects compete for recognition across saccades, but only if they are task-relevant. This reveals an attentional mechanism of task-driven object recognition that is interlaced with active saccade-mediated vision. |
Henry Railo; Henri Olkoniemi; Enni Eeronheimo; Oona Pääkkönen; Juho Joutsa; Valtteri Kaasinen Dopamine and eye movement control in Parkinson's disease: Deficits in corollary discharge signals? Journal Article In: PeerJ, vol. 6, pp. 1–25, 2018. @article{Railo2018, Movement in Parkinson's disease (PD) is fragmented, and the patients depend on visual information in their behavior. This suggests that the patients may have deficits in internally monitoring their own movements. Internal monitoring of movements is assumed to rely on corollary discharge signals that enable the brain to predict the sensory consequences of actions. We studied early-stage PD patients (N = 14), and age-matched healthy control participants (N = 14) to examine whether PD patients reveal deficits in updating their sensory representations after eye movements. The participants performed a double-saccade task where, in order to accurately fixate a second target, the participant must correct for the displacement caused by the first saccade. In line with previous reports, the patients had difficulties in fixating the second target when the eye movement was performed without visual guidance. Furthermore, the patients had difficulties in taking into account the error in the first saccade when making a saccade toward the second target, especially when eye movements were made toward the side with dominant motor symptoms. Across PD patients, the impairments in saccadic eye movements correlated with the integrity of the dopaminergic system as measured with [123I]FP-CIT SPECT: Patients with lower striatal (caudate, anterior putamen, and posterior putamen) dopamine transporter binding made larger errors in saccades. This effect was strongest when patients made memory-guided saccades toward the second target. Our results provide tentative evidence that the motor deficits in PD may be partly due to deficits in internal monitoring of movements. |
Meike Ramon; Nayla Sokhn; Junpeng Lao; Roberto Caldara Decisional space determines saccadic reaction times in healthy observers and acquired prosopagnosia Journal Article In: Cognitive Neuropsychology, vol. 35, no. 5-6, pp. 304–313, 2018. @article{Ramon2018a, Determining the familiarity and identity of a face have been considered as independent processes. Covert face recognition in cases of acquired prosopagnosia, as well as rapid detection of familiarity have been taken to support this view. We tested P.S. a well-described case of acquired prosopagnosia, and two healthy controls (her sister and daughter) in two saccadic reaction time (SRT) experiments. Stimuli depicted their family members and well-matched unfamiliar distractors in the context of binary gender, or familiarity decisions. Observers' minimum SRTs were estimated with Bayesian approaches. For gender decisions, P.S. and her daughter achieved sufficient performance, but displayed different SRT distributions. For familiarity decisions, her daughter exhibited above chance level performance and minimum SRTs corresponding to those reported previously in healthy observers, while P.S. performed at chance. These findings extend previous observations, indicating that decisional space determines performance in both the intact and impaired face processing system. |
Leon C. Reteig; Tomas Knapen; Floris J. F. W. Roelofs; K. Richard Ridderinkhof; Heleen A. Slagter No evidence that frontal eye field tDCS affects latency or accuracy of prosaccades Journal Article In: Frontiers in Neuroscience, vol. 12, pp. 617, 2018. @article{Reteig2018, Transcranial direct current stimulation (tDCS) may be used to directly affect neural activity from outside of the skull. However, its exact physiological mechanisms remain elusive, particularly when applied to new brain areas. The frontal eye field (FEF) has rarely been targeted with tDCS, even though it plays a crucial role in control of overt and covert spatial attention. Here we investigate whether tDCS over the FEF can affect the latency and accuracy of saccadic eye movements. 26 participants performed a prosaccade task in which they made eye movements to a sudden-onset eccentric visual target (lateral saccades). After each lateral saccade, they made an eye movement back to the center (center saccades). The task was administered before, during and after anodal or cathodal tDCS over the FEF, in a randomized, double-blind, within-subject design. One previous study (Kanai et al., 2012) found that anodal tDCS over the FEF decreased the latency of saccades contralateral to the stimulated hemisphere. We did not find the same effect: neither anodal nor cathodal tDCS influenced the latency of lateral saccades. tDCS also did not affect accuracy of lateral saccades (saccade endpoint deviation and saccade endpoint variability). For center saccades, we found some differences between the anodal and cathodal sessions, but these were not consistent across analyses (latency, endpoint variability), or were already present before tDCS onset (endpoint deviation). We tried to improve on the design of Kanai et al. (2012) in several ways, including the tDCS duration and electrode montage, which could explain the discrepant results. Our findings add to a growing number of null results, which have sparked concerns that tDCS outcomes are highly variable. Future studies should aim to establish the boundary conditions for frontal eye field tDCS to be effective, in addition to increasing sample size and adding additional controls such as a sham condition. At present, we conclude that it is unclear whether eye movements or other aspects of spatial attention can be affected through tDCS of the frontal eye fields. |
Johannes Rosskopf; Martin Gorges; Hans Peter Müller; Elmar H. Pinkhardt; Albert C. Ludolph; Jan Kassubek Hyperconnective and hypoconnective cortical and subcortical functional networks in multiple system atrophy Journal Article In: Parkinsonism and Related Disorders, vol. 49, no. 2017, pp. 75–80, 2018. @article{Rosskopf2018, Introduction: In multiple system atrophy (MSA), the organization of the functional brain connectivity within cortical and subcortical networks and its clinical correlates remains to be investigated. Methods: Whole-brain based ‘resting-state' fMRI data were obtained from 22 MSA patients (11 MSA-C, 11 MSA-P) and 22 matched healthy controls, together with standardized clinical assessment and video-oculographic recordings (EyeLink®). Results: MSA patients vs. controls showed significantly higher ponto-cerebellar functional connectivity and lower default mode network connectivity (p <.05, corrected). No differences were observed in the motor network and in the control network. The higher the ponto-cerebellar network functional connectivity was, the more pronounced was smooth pursuit impairment. Conclusion: This functional connectivity analysis supports a network-dependent combination of hyper- and hypoconnectivity states in MSA, in agreement with adaptive compensatory responses (hyperconnectivity) and a function disconnection syndrome (hypoconnectivity) that may occur in a consecutive sequence. |
Jason M. Samonds; Wilson S. Geisler; Nicholas J. Priebe Natural image and receptive field statistics predict saccade sizes Journal Article In: Nature Neuroscience, vol. 21, no. 11, pp. 1591–1599, 2018. @article{Samonds2018, Humans and other primates sample the visual environment using saccadic eye movements that shift a high-resolution fovea toward regions of interest to create a clear perception of a scene across fixations. Many mammals, however, like mice, lack a fovea, which raises the question of why they make saccades. Here we describe and test the hypothesis that saccades are matched to natural scene statistics and to the receptive field sizes and adaptive properties of neural populations. Specifically, we determined the minimum amplitude of saccades in natural scenes necessary to provide uncorrelated inputs to model neural populations. This analysis predicts the distributions of observed saccade sizes during passive viewing for nonhuman primates, cats, and mice. Furthermore, disrupting the development of receptive field properties by monocular deprivation changed saccade sizes consistent with this hypothesis. Therefore, natural-scene statistics and the neural representation of natural images appear to be critical factors guiding saccadic eye movements. |
Ricky R. Savjani; Sucharit Katyal; Elizabeth Halfen; Jung Hwan Kim; David Ress Polar-angle representation of saccadic eye movements in human superior colliculus Journal Article In: NeuroImage, vol. 171, pp. 199–208, 2018. @article{Savjani2018, The superior colliculus (SC) is a layered midbrain structure involved in directing both head and eye movements and coordinating visual attention. Although a retinotopic organization for the mediation of saccadic eye-movements has been shown in monkey SC, in human SC the topography of saccades has not been confirmed. Here, a novel experimental paradigm was performed by five participants (one female) while high-resolution (1.2-mm) functional magnetic resonance imaging was used to measure activity evoked by saccadic eye movements within human SC. Results provide three critical observations about the topography of the SC: (1) saccades along the superior-inferior visual axis are mapped across the medial-lateral anatomy of the SC; (2) the saccadic eye-movement representation is in register with the retinotopic organization of visual stimulation; and (3) activity evoked by saccades occurs deeper within SC than that evoked by visual stimulation. These approaches lay the foundation for studying the organization of human subcortical – and enhanced cortical mapping – of eye-movement mechanisms. |
Kristin M. Pelczarski; Anna Tendera; Matthew Dye; Torrey M. Loucks Delayed phonological encoding in stuttering: Evidence from eye tracking Journal Article In: Language and Speech, vol. 62, no. 3, pp. 475–493, 2018. @article{Pelczarski2018, Stuttering is a multifactorial disorder that is characterized by disruptions in the forward flow of speech believed to be caused by differences in the motor and linguistic systems. Several psycholinguistic theories of stuttering suggest that delayed or disrupted phonological encoding contributes to stuttered speech. However, phonological encoding remains difficult to measure without controlling for the involvement of the speech-motor system. Eye-tracking is proposed to be a reliable approach for measuring phonological encoding duration while controlling for the influence of speech production. Eighteen adults who stutter and 18 adults who do not stutter read nonwords under silent and overt conditions. Eye-tracking was used to measure dwell time, number of fixations, and response time. Adults who stutter demonstrated significantly more fixations and longer dwell times during overt reading than adults who do not stutter. In the silent condition, the adults who stutter produced more fixations on the nonwords than adults who do not stutter, but dwell-time differences were not found. Overt production may have resulted in additional requirements at the phonological and phonetic levels of encoding for adults who stutter. Direct measurement of eye-gaze fixation and dwell time suggests that adults who stutter require additional processing that could potentially delay or interfere with phonological-to-motor encoding. |
Barbara Poletti; Laura Carelli; Andrea Faini; Federica Solca; Paolo Meriggi; Annalisa Lafronza; Luciana Ciringione; Elisa Pedroli; Nicola Ticozzi; Andrea Ciammola; Pietro Cipresso; Giuseppe Riva; Vincenzo Silani The Arrows and Colors Cognitive Test (ACCT): A new verbal-motor free cognitive measure for executive functions in ALS Journal Article In: PLoS ONE, vol. 13, no. 8, pp. e0200953, 2018. @article{Poletti2018, Background and objective: The presence of executive deficits in patients with Amyotrophic Lateral Sclerosis is well established, even if standardized measures are difficult to obtain due to progressive physical disability of the patients. We present clinical data concerning a newly developed measure of cognitive flexibility, administered by means of Eye-Tracking (ET) technology in order to bypass verbal-motor limitations. Methods: 21 ALS patients and 21 age-and education-matched healthy subjects participated in an ET-based cognitive assessment, including a newly developed test of cognitive flexibility (Arrows and Colors Cognitive Test–ACCT) and other oculomotor-driven measures of cognitive functions. A standard screening of frontal and working memory abilities and global cognitive efficiency was administered to all subjects, in addition to a psychological self-rated assessment. For ALS patients, a clinical examination was also performed. Results: ACCT successfully discriminated between patients and healthy controls, mainly concerning execution times obtained at different subtests. A qualitative analysis performed on error distributions in patients highlighted a lower prevalence of perseverative errors, with respect to other type of errors. Correlations between ACCT and other ET-based frontal-executive measures were significant and involved different frontal sub-domains. Limited correlations were observed between ACCT and standard ‘paper and pencil' cognitive tests. Conclusions: The newly developed ET-based measure of cognitive flexibility could be a useful tool to detect slight frontal impairments in non-demented ALS patients by bypassing verbal-motor limitations through the oculomotor-driven administration. The findings reported in the present study represent the first contribution towards the development of a full verbal-motor free executive test for ALS patients. |
Meike Ramon; Nayla Sokhn; Junpeng Lao; Roberto Caldara Decisional space modulates saccadic reaction times towards personally familiar faces in healthy observers and acquired prosopagnosia Journal Article In: Journal of Vision, vol. 18, no. 10, pp. 1097, 2018. @article{Ramon2018, Determining the familiarity and identity of a face have been considered as independent processes. Covert face recognition in cases of acquired prosopagnosia, as well as rapid detection of familiarity have been taken to support this view. We tested P.S. a well-described case of acquired prosopagnosia, and two healthy controls (her sister and daughter) in two saccadic reaction time (SRT) experiments. Stimuli depicted their family members and well-matched unfamiliar distractors in the context of binary gender, or familiarity decisions. Observers' minimum SRTs were estimated with Bayesian approaches. For gender decisions, P.S. and her daughter achieved sufficient performance, but displayed different SRT distributions. For familiarity decisions, her daughter exhibited above chance level performance and minimum SRTs corresponding to those reported previously in healthy observers, while P.S. performed at chance. These findings extend previous observations, indicating that decisional space determines performance in both the intact and impaired face processing system. |
Mariel Roberts; Brandon K. Ashinoff; F. Xavier Castellanos; Marisa Carrasco When attention is intact in adults with ADHD Journal Article In: Psychonomic Bulletin & Review, vol. 25, no. 4, pp. 1423–1434, 2018. @article{Roberts2018, Is covert visuospatial attention—selective processing of information in the absence of eye movements—preserved in adults with attention-deficit/hyperactivity disorder (ADHD)? Previous findings are inconclusive due to inconsistent terminology and suboptimal methodology. To settle this question, we used well-established spatial cueing protocols to investigate the perceptual effects of voluntary and involuntary attention on an orientation discrimination task for a group of adults with ADHD and their neurotypical age-matched and gender-matched controls. In both groups, voluntary attention significantly improved accuracy and decreased reaction times at the relevant location, but impaired accuracy and slowed reaction times at irrelevant locations, relative to a distributed attention condition. Likewise, involuntary attention improved accuracy and speeded responses. Critically, the magnitudes of all these orienting and reorienting attention effects were indistinguishable between groups. Thus, these counterintuitive findings indicate that spatial covert attention remains functionally intact in adults with ADHD. |
Alasdair I. Ross; Thomas Schenk; Jutta Billino; Mary J. Macleod; Constanze Hesse Avoiding unseen obstacles: Subcortical vision is not sufficient to maintain normal obstacle avoidance behaviour during reaching Journal Article In: Cortex, vol. 98, pp. 177–193, 2018. @article{Ross2018, Previous research found that a patient with cortical blindness (homonymous hemianopia) was able to successfully avoid an obstacle placed in his blind field, despite reporting no conscious awareness of it [Striemer, C. L., Chapman, C. S., & Goodale, M. A., 2009, PNAS, 106(37), 15996–16001]. This finding led to the suggestion that dorsal stream areas, that are assumed to mediate obstacle avoidance behaviour, may obtain their visual input primarily from subcortical pathways. Hence, it was suggested that normal obstacle avoidance behaviour can proceed without input from the primary visual cortex. Here we tried to replicate this finding in a group of patients (N = 6) that suffered from highly circumscribed lesions in the occipital lobe (including V1) that spared the subcortical structures that have been associated with action-blindsight. We also tested if obstacle avoidance behaviour differs depending on whether obstacles are placed only in the blind field or in both the blind and intact visual field of the patients simultaneously. As expected, all patients successfully avoided obstacles placed in their intact visual field. However, none of them showed reliable avoidance behaviour – as indicated by adjustments in the hand trajectory in response to obstacle position – for obstacles placed in their blind visual field. The effects were not dependent on whether one or two obstacles were present. These findings suggest that behaviour in complex visuomotor tasks relies on visual input from occipital areas. |
Rachel Ryskin; Zhenghan Qi; Natalie V. Covington; Melissa Duff; Sarah Brown-Schmidt Knowledge and learning of verb biases in amnesia Journal Article In: Brain and Language, vol. 180-182, pp. 62–83, 2018. @article{Ryskin2018, Verb bias—the co-occurrence frequencies between a verb and the syntactic structures it may appear with—is a critical and reliable linguistic cue for online sentence processing. In particular, listeners use this information to disambiguate sentences with multiple potential syntactic parses (e.g., Feel the frog with the feather.). Further, listeners dynamically update their representations of specific verbs in the face of new evidence about verb-structure co-occurrence. Yet, little is known about the biological memory systems that support the use and dynamic updating of verb bias. We propose that hippocampal-dependent declarative (relational) memory represents a likely candidate system because it has been implicated in the flexible binding of relational co-occurrences and in statistical learning. We explore this question by testing patients with severe and selective deficits in declarative memory (anterograde amnesia), and demographically matched healthy participants, in their on-line interpretation of ambiguous sentences and the ability to update their verb bias with experience. We find that (1) patients and their healthy counterparts use existing verb bias to successfully interpret on-line ambiguity, however (2) unlike healthy young adults, neither group updated these biases in response to recent exposure. These findings demonstrate that using existing representations of verb bias does not necessitate involvement of the declarative memory system, but leave open the question of whether the ability to update representations of verb-specific biases requires hippocampal engagement. |
Dongfang Shen; Min Li; Ying Zhou; Lixin Liang; Lu Zhang; Wangzikang Zhang; Mingsha Zhang; Yujun Pan Deviation of spatial representation and asymmetric saccadic reaction time in Hemi-Parkinson's disease Journal Article In: Frontiers in Aging Neuroscience, vol. 10, pp. 84, 2018. @article{Shen2018c, Background: Patients with Parkinson's disease (PD) commonly show spatially asymmetric behaviors, such as veering while attempting to walk in a straight line. While there is general agreement that the lateral motor dysfunction contributes to asymmetric behaviors in PD, it is dispute regarding whether the spatial perception is also biased. In addition, it is not clear whether PD impairs the speed of spatial information process, i.e., the efficiency of information process. Objectives: To assess the visuospatial representation and efficiency of spatial information processing in hemi-PD. Methods: Two saccadic tasks were employed: non-spatial cue evoked saccade and spatial cue evoked saccade. In the former task, an identical visual stimulus (appeared on the body mid-sagittal plane) was artificially associated with a fixed saccadic target (left or right) in a given session. In the latter task, subjects were instructed to make a rightward or leftward saccade based on the perceived location of a visual cue (left vs. right side of the body mid-sagittal plane). We estimated the location of subjective straight ahead (SSA) for each subject by using a psychometric fitting function to fit the location judgment results, enabling evaluation of the symmetry of representation between the left and right hemifields. In addition, since the locations of saccadic targets were same in these two tasks, thus, for each individual subject, the elongated saccadic reaction time (SRT) in the latter task, comparing with the former one, mainly reflects the time spent on judgment of the spatial location of visual cue, i.e., spatial perception. We also assessed the efficiency of spatial perception between two hemispheres, through comparing the normalized SRT (i.e., SRT difference between two tasks) between trials with leftward and rightward judgments. Results: Compared with healthy control subjects (HCs), the SSA was shifted to the contralesional side in both left onset PD (LPD, lesion of right substantia nigra) and right onset PD (RPD, lesion of left substantia nigra) patients. The process of spatial information was significantly longer when a spatial cue appeared in the contralesional hemifield. Conclusions: Patients with hemi-PD showed biased visuospatial representation between left and right hemifields and decreased the efficiency of spatial information processing in the contralesional side. Such results indicate that the hemi-PD impairs both spatial representation and the efficiency of spatial information process, which might contribute to asymmetric behaviors. |
Tarkeshwar Singh; Christopher M. Perry; Stacy L. Fritz; Julius Fridriksson; Troy M. Herter Eye movements interfere with limb motor control in stroke survivors Journal Article In: Neurorehabilitation and Neural Repair, vol. 32, no. 8, pp. 724–734, 2018. @article{Singh2018, Background. Humans use voluntary eye movements to actively gather visual information during many activities of daily living, such as driving, walking, and preparing meals. Most stroke survivors have difficulties performing these functional motor tasks, and we recently demonstrated that stroke survivors who require many saccades (rapid eye movements) to plan reaching movements exhibit poor motor performance. However, the nature of this relationship remains unclear. Objective. Here we investigate if saccades interfere with speed and smoothness of reaching movements in stroke survivors, and if excessive saccades are associated with difficulties performing functional tasks. Methods. We used a robotic device and eye tracking to examine reaching and saccades in stroke survivors and age-matched controls who performed the Trail Making Test, a visuomotor task that uses organized patterns of saccades to plan reaching movements. We also used the Stroke Impact Scale to examine difficulties performing functional tasks. Results. Compared with controls, stroke survivors made many saccades during ongoing reaching movements, and most of these saccades closely preceded transient decreases in reaching speed. We also found that the number of saccades that stroke survivors made during ongoing reaching movements was strongly associated with slower reaching speed, decreased reaching smoothness, and greater difficulty performing functional tasks. Conclusions. Our findings indicate that poststroke interference between eye and limb movements may contribute to difficulties performing functional tasks. This suggests that interventions aimed at treating impaired organization of eye movements may improve functional recovery after stroke. |
Christine N. Smith; Larry R. Squire Awareness of what is learned as a characteristic of hippocampus-dependent memory Journal Article In: Proceedings of the National Academy of Sciences, vol. 115, no. 47, pp. 11947–11952, 2018. @article{Smith2018b, We explored the relationship between memory performance and conscious knowledge (or awareness) of what has been learned in memory-impaired patients with hippocampal lesions or larger medial temporal lesions. Participants viewed familiar scenes or familiar scenes where a change had been introduced. Patients identified many fewer of the changes than controls. Across all of the scenes, controls preferentially directed their gaze toward the regions that had been changed whenever they had what we term robust knowledge about the change: They could identify that a change occurred, report what had changed, and indicate where the change occurred. Preferential looking did not occur when they were unaware of the change or had only partial knowledge about it. The patients, overall, did not direct their gaze toward the regions that had been changed, but on the few occasions when they had robust knowledge about the change they (like controls) did exhibit this effect. Patients did not exhibit this effect when they were unaware of the change or had partial knowledge. The findings support the idea that awareness of what has been learned is a key feature of hippocampus-dependent memory. |
Kimberly G. Smith; Joseph Schmidt; Bin Wang; John M. Henderson; Julius Fridriksson Task-related differences in eye movements in individuals with aphasia Journal Article In: Frontiers in Psychology, vol. 9, pp. 2430, 2018. @article{Smith2018a, Background: Neurotypical young adults show task-based modulation and stability of their eye movements across tasks. This study aimed to determine whether persons with aphasia (PWA) modulate their eye movements and show stability across tasks similarly to control participants. Methods: Forty-eight PWA and age-matched control participants completed four eye-tracking tasks: scene search, scene memorization, text-reading, and pseudo-reading. Results: Main effects of task emerged for mean fixation duration, saccade amplitude, and standard deviations of each, demonstrating task-based modulation of eye movements. Group by task interactions indicated that PWA produced shorter fixations relative to controls. This effect was most pronounced for scene memorization and for individuals who recently suffered a stroke. PWA produced longer fixations, shorter saccades, and less variable eye movements in reading tasks compared to controls. Three-way interactions of group, aphasia subtype, and task also emerged. Text-reading and scene memorization were particularly effective at distinguishing aphasia subtype. Persons with anomic aphasia showed a reduction in reading saccade amplitudes relative to their respective control group and other PWA. Persons with conduction/Wernicke's aphasia produced shorter scene memorization fixations relative to controls or PWA of other subtypes, suggesting a memorization specific effect. Positive correlations across most tasks emerged for fixation duration and did not significantly differ between controls and PWA. Conclusion: PWA generally produced shorter fixations and smaller saccades relative to controls particularly in scene memorization and text-reading, respectively. The effect was most pronounced recently after a stroke. Selectively in reading tasks, PWA produced longer fixations and shorter saccades relative to controls, consistent with reading difficulty. PWA showed task-based modulation of eye movements, though the pattern of results was somewhat abnormal relative to controls. All subtypes of PWA also demonstrated task-based modulation of eye movements. However, persons with anomic aphasia showed reduced modulation of saccade amplitude and smaller reading saccades, possibly to improve reading comprehension. Controls and PWA generally produced stabile fixation durations across tasks and did not differ in their relationship across tasks. Overall, these results suggest there is potential to differentiate among PWA with varying subtypes and from controls using eye movement measures of task-based modulation, especially reading and scene memorization tasks. |
Oleg Solopchuk; Moustapha Sebti; Céline Bouvy; Charles-Etienne Benoit; Thibault Warlop; Anne Jeanjean; Alexandre Zénon Locus Coeruleus atrophy doesn't relate to fatigue in Parkinson's disease Journal Article In: Scientific Reports, vol. 8, pp. 12381, 2018. @article{Solopchuk2018, Fatigue is a frequent complaint among healthy population and one of the earliest and most debilitating symptoms in Parkinson's disease (PD). Earlier studies have examined the role of dopamine and serotonin in pathogenesis of fatigue, but the plausible role of noradrenalin (NA) remains underexplored. We investigated the relationship between fatigue in Parkinsonian patients and the extent of degeneration of Locus Coeruleus (LC), the main source of NA in the brain. We quantified LC and Substantia Nigra (SN) atrophy using neuromelanin-sensitive imaging, analyzed with a novel, fully automated algorithm. We also assessed patients' fatigue, depression, sleep disturbance and vigilance. We found that LC degeneration correlated with the levels of depression and vigilance but not with fatigue, while fatigue correlated weakly with atrophy of SN. These results indicate that LC degeneration in Parkinson's disease is unlikely to cause fatigue, but may be involved in mood and vigilance alterations. |
Tobias Staudigl; Marcin Leszczynski; Joshua Jacobs; Sameer A. Sheth; Charles E. Schroeder; Ole Jensen; Christian F. Doeller Hexadirectional modulation of high-frequency electrophysiological activity in the human anterior medial temporal lobe maps visual space Journal Article In: Current Biology, vol. 28, pp. 1–5, 2018. @article{Staudigl2018, Grid cells are one of the core building blocks of spatial navigation [1]. Single-cell recordings of grid cells in the rodent entorhinal cortex revealed hexagonal coding of the local environment during spatial navigation [1]. Grid-like activity has also been identified in human single-cell recordings during virtual navigation [2]. Human fMRI studies further provide evidence that grid-like signals are also accessible on a macroscopic level [3–7]. Studies in both nonhuman primates [8] and humans [9, 10] suggest that grid-like coding in the entorhinal cortex generalizes beyond spatial navigation during locomotion, providing evidence for grid-like mapping of visual space during visual exploration—akin to the grid cell positional code in rodents during spatial navigation. However, electrophysiological correlates of the grid code in humans remain unknown. Here, we provide evidence for grid-like, hexadirectional coding of visual space by human high-frequency activity, based on two independent datasets: non-invasive magnetoencephalography (MEG) in healthy subjects and entorhinal intracranial electroencephalography (EEG) recordings in an epileptic patient. Both datasets consistently show a hexadirectional modulation of broadband high-frequency activity (60–120 Hz). Our findings provide first evidence for a grid-like MEG signal, indicating that the human entorhinal cortex codes visual space in a grid-like manner [8–10], and support the view that grid coding generalizes beyond environmental mapping during locomotion [4–6, 11]. Due to their millisecond accuracy, MEG recordings allow linking of grid-like activity to epochs during relevant behavior, thereby opening up the possibility for new MEG-based investigations of grid coding at high temporal resolution. |
David R. Howell; Anna N. Brilliant; Eileen P. Storey; Olivia E. Podolak; William P. Meehan; Christina L. Master Objective eye tracking deficits following concussion for youth seen in a sports medicine setting Journal Article In: Journal of Child Neurology, vol. 33, no. 12, pp. 794–800, 2018. @article{Howell2018, Quantification of visual deficits may help to identify dysfunction following concussion. We evaluated eye-tracking measurements among adolescents within 10 days of concussion and healthy control participants. Patients who reported to 2 tertiary care sport concussion clinics within 10 days of concussion completed an objective eye tracking assessment. Seventy-nine participants completed the study, 44 with concussion (mean age = 14.1 ± 2.2 years, 39% female) and 35 controls (mean age = 14.3 ± 2.4 years, 57% female). Right eye skew along the bottom of the screen was significantly higher for the concussion group compared to controls (median = 0.022 [interquartile range = –0.263, 0.482] vs 0.377 [interquartile range = –0.574, –0.031]; P = .002), but not the left eye. Among the variables investigated, right eye skew was altered for adolescents with a concussion. Visual function is an important component in the postconcussion evaluation, and identifying deficits soon after injury may allow for earlier specialist referral and intervention. |
Rosalind Hutchings; Romina Palermo; Jason Bruggemann; John R. Hodges; Olivier Piguet; Fiona Kumfor Looking but not seeing: Increased eye fixations in behavioural-variant frontotemporal dementia Journal Article In: Cortex, vol. 103, pp. 71–80, 2018. @article{Hutchings2018, Face processing plays a central role in human communication, with the eye region a particularly important cue for discriminating emotions. Indeed, reduced attention to the eyes has been argued to underlie social deficits in a number of clinical populations. Despite well-established impairments in facial affect recognition in behavioural-variant fronto-temporal dementia, whether these patients also have perturbed facial scanning is yet to be investigated. The current study employed eye tracking to record visual scanning of faces in 20 behavioural-variant frontotemporal dementia patients and 21 controls. Remarkably, behavioural-variant frontotemporal dementia patients displayed more fixations to the eyes of emotional faces, compared to controls. Neural regions associated with fixations to the eyes included the left inferior frontal gyrus, right cerebellum and middle temporal gyrus. Our study is the first to show such compensatory functions in behavioural-variant fron-totemporal dementia and suggest a feedback-style network, including anterior and posterior brain regions, is involved in early face processing. |
Leyla Isik; Jedediah M. Singer; Joseph R. Madsen; Nancy Kanwisher; Gabriel Kreiman What is changing when: Decoding visual information in movies from human intracranial recordings Journal Article In: NeuroImage, vol. 180, pp. 147–159, 2018. @article{Isik2018, The majority of visual recognition studies have focused on the neural responses to repeated presentations of static stimuli with abrupt and well-defined onset and offset times. In contrast, natural vision involves unique renderings of visual inputs that are continuously changing without explicitly defined temporal transitions. Here we considered commercial movies as a coarse proxy to natural vision. We recorded intracranial field potential signals from 1,284 electrodes implanted in 15 patients with epilepsy while the subjects passively viewed commercial movies. We could rapidly detect large changes in the visual inputs within approximately 100 ms of their occurrence, using exclusively field potential signals from ventral visual cortical areas including the inferior temporal gyrus and inferior occipital gyrus. Furthermore, we could decode the content of those visual changes even in a single movie presentation, generalizing across the wide range of transformations present in a movie. These results present a methodological framework for studying cognition during dynamic and natural vision. |
Todd Jackson; Lin Su; Yang Wang Effects of higher versus lower threat contexts on pain-related visual attention biases: An eye-tracking study of chronic pain Journal Article In: Journal of Pain, vol. 19, no. 6, pp. 649–659, 2018. @article{Jackson2018, In this research, we examined effects of higher versus lower threat contexts on attention biases in more and less pain-fearful chronic pain subgroups via eye-tracking methodology. Within a mixed chronic pain sample (69 women, 29 men), biases in orienting and maintenance of visual attention were assessed during the standardized image pair presentation phase (2,000 ms) of a modified visual dot probe task featuring painful-neutral (P-N) image pairs (lower threat context) and a parallel task in which these P-N pairs cued potential pain (higher threat context). Across both tasks, participants more often oriented toward, gazed longer at, and made more unique fixations upon pain images during P-N pair presentations. Although trait-based fear of pain was not related to any gaze bias index in either task, between task analyses indicated the sample reported more state fear, directed their initial gaze less often, and displayed longer overall gaze durations toward pain images in the higher threat context in which P-N trials signaled potential pain. Results supported the threat interpretation model premise that persons with chronic pain have difficulty disengaging from moderately threatening visual painful cues. |
Norbert Kathmann; Julia Klawohn; Leonhard Lennertz; Ulrich Ettinger; Anja Riesel; Christian Kaufmann; Inga Meyhöfer; Michael Wagner; Rosa Grützmann; Katharina Bey; Stephan Heinzel Impaired antisaccades in obsessive-compulsive disorder: Evidence from meta-analysis and a large empirical study Journal Article In: Frontiers in Psychiatry, vol. 9, pp. 284, 2018. @article{Kathmann2018, Increasing evidence indicates that patients with obsessive-compulsive disorder (OCD) exhibit alterations in fronto-striatal circuitry. Performance deficits in the antisaccade task would support this model, but results from previous small-scale studies have been inconclusive as either increased error rates, prolonged antisaccade latencies, both or neither have been reported in OCD patients. In order to address this issue, we investigated antisaccade performance in a large sample of OCD patients (n = 169) and matched control subjects (n = 183). As impaired antisaccade performance constitutes a potential endophenotype of OCD, unaffected first-degree relatives of OCD patients (n = 100) were assessed, as well. Furthermore, we conducted a quantitative meta-analysis to integrate our data with previous findings. In the empirical study, OCD patients exhibited significantly increased antisaccade latencies, intra-subject variability (ISV) of antisaccade latencies, and antisaccade error rates. The latter effect was driven by errors with express latency (80–130ms), as patients did not differ significantly from controls with regards to regular errors (>130ms). Notably, unaffected relatives of OCD patients showed elevated antisaccade express error rates and increased ISV of antisaccade latencies, as well. Antisaccade performance was not associated with state anxiety within groups. Among relatives, however, we observed a significant correlation between antisaccade error rate and harm avoidance. Medication status of OCD patients, symptom severity, depressive comorbidity, comorbid anxiety disorders and OCD symptom dimensions did not significantly affect antisaccade performance. Meta-analysis of 10 previous and the present empirical study yielded a medium-sized effect (SMD = 0.48, p < 0.001) for higher error rates in OCD patients, while the effect for latencies did not reach significance owing to strong heterogeneity (SMD = 0.51 |
Masataka Kikuchi; Kenichiro Miura; Kentaro Morita; Hidenaga Yamamori; Michiko Fujimoto; Masashi Ikeda; Yuka Yasuda; Akihiro Nakaya; Ryota Hashimoto Genome-wide association analysis of eye movement dysfunction in schizophrenia Journal Article In: Scientific Reports, vol. 8, pp. 12347, 2018. @article{Kikuchi2018, Eye movements are considered endophenotypes of schizophrenia. However, the genetic factors underlying eye movement are largely unknown. In this study, we explored the susceptibility loci for four eye movement scores: the scanpath length during the free viewing test (SPL), the horizontal position gain during the fast Lissajous paradigm of the smooth pursuit test (HPG), the duration of fixations during the far distractor paradigm of the fixation stability test (DF) and the integrated eye movement score of those three scores (EMS). We found 16 SNPs relevant to the HPG that were located in 3 genomic regions (1q21.3, 7p12.1 and 20q13.12) in the patient group; however, these SNPs were intronic or intergenic SNPs. To determine whether these SNPs occur in functional non-coding regions (i.e., enhancer or promoter regions), we examined the chromatin status on the basis of publicly available epigenomic data from 127 tissues or cell lines. This analysis suggested that the SNPs on 1q21.3 and 20q13.12 are in enhancer or promoter regions. Moreover, we performed an analysis of expression quantitative trait loci (eQTL) in human brain tissues using a public database. Finally, we identified significant eQTL effects for all of the SNPs at 1q21.3 and 20q13.12 in particular brain regions. |
Esther S. Kim; Salima Suleman; Tammy Hopper Cognitive effort during a short-term memory (STM) task in individuals with aphasia Journal Article In: Journal of Neurolinguistics, vol. 48, pp. 190–198, 2018. @article{Kim2018b, People with aphasia (PWA) have been shown to demonstrate limited short-term memory (STM) span capacity, but little is known about the degree of cognitive effort PWA expend when completing STM tasks. For decades, researchers have used task-evoked pupillary responses (TEPRs) to infer cognitive effort; pupil size increases as the difficulty of a task increases. The purpose of this study was to examine TEPRs while PWA and healthy control participants completed a STM picture span task. Sixteen PWA and 16 demographically matched control participants completed paper-based and computer-based versions of a picture span task. Measures of pupil size were collected using an eye-tracking system during the computer-based task. Both PWA and control participants demonstrated increased pupil size as STM demands increased. The two groups did not differ in pupil size across different span levels; however, PWA performed significantly poorer than matched controls in terms of behavioural accuracy scores. This suggests that although PWA exerted similar amounts of effort to control participants as task demands increased, they did not show a corresponding increase in accuracy. These data provide support for the feasibility of using TEPRs to investigate cognitive effort in PWA. In conjunction with behavioural performance measures, measures of cognitive effort may provide a holistic picture of cognitive and linguistic functioning in PWA. |
Radek Kolecki; Vikalpa M. Dammavalam; Abdullah Bin Zahid; Molly E. Hubbard; Osamah Choudhry; Marleen Reyes; ByoungJun Han; Tom Wang; Paraskevi Vivian Papas; Aylin Adem; Emily North; David T. Gilbertson; Douglas Kondziolka; Jason H. Huang; Paul P. Huang; Uzma Samadani Elevated intracranial pressure and reversible eye-tracking changes detected while viewing a film clip Journal Article In: Journal of Neurosurgery, vol. 128, pp. 811–818, 2018. @article{Kolecki2018, OBJECTIVE: The precise threshold differentiating normal and elevated intracranial pressure (ICP) is variable among individuals. In the context of several pathophysiological conditions, elevated ICP leads to abnormalities in global cerebral functioning and impacts the function of cranial nerves (CNs), either or both of which may contribute to ocular dysmotil- ity. The purpose of this study was to assess the impact of elevated ICP on eye-tracking performed while patients were watching a short film clip. METHODS: Awake patients requiring placement of an ICP monitor for clinical purposes underwent eye tracking while watching a 220-second continuously playing video moving around the perimeter of a viewing monitor. Pupil position was recorded at 500 Hz and metrics associated with each eye individually and both eyes together were calculated. Linear regression with generalized estimating equations was performed to test the association of eye-tracking metrics with changes in ICP. RESULTS: Eye tracking was performed at ICP levels ranging from -3 to 30 mm Hg in 23 patients (12 women, 11 men, mean age 46.8 years) on 55 separate occasions. Eye-tracking measures correlating with CN function linearly decreased with increasing ICP (p < 0.001). Measures for CN VI were most prominently affected. The area under the curve (AUC) for eye-tracking metrics to discriminate between ICP < 12 and ≥ 12 mm Hg was 0.798. To discriminate an ICP < 15 from ≥ 15 mm Hg the AUC was 0.833, and to discriminate ICP < 20 from ≥ 20 mm Hg the AUC was 0.889. CONCLUSIONS: Increasingly elevated ICP was associated with increasingly abnormal eye tracking detected while patients were watching a short film clip. These results suggest that eye tracking may be used as a noninvasive, automatable means to quantitate the physiological impact of elevated ICP, which has clinical application for assessment of shunt malfunction, pseudotumor cerebri, concussion, and prevention of second-impact syndrome. |
Catarina C. Kordsachia; Izelle Labuschagne; Julie C. Stout Visual scanning of the eye region of human faces predicts emotion recognition performance in Huntington's disease Journal Article In: Neuropsychology, vol. 32, no. 3, pp. 356–365, 2018. @article{Kordsachia2018, Objective: Previous research has consistently shown that the ability to recognize emotions from facial expressions is impaired in Huntington's disease (HD). The aim of this study was to examine whether people with the gene expansion for HD visually scan the most emotionally informative features of human faces less than unaffected individuals, and whether altered visual scanning predicts emotion recognition in HD beyond general disease-related decline. Method: We recorded eye movements of 25 participants either in the late premanifest or early stage of HD and 25 age-matched healthy control participants during a face-viewing task. The task involved the viewing of pictures depicting human faces with angry, disgusted, fearful, happy, and neutral expressions, and evaluating each face on a valence rating scale. For data analysis, we defined 2 regions of interest (ROIs) on each picture, including an eye-ROI and a nose/mouth-ROI. Emotion recognition abilities were measured using an established emotion-recognition task and general disease-related decline was measured using the UHDRS motor score. Results: Compared to the control participants, the HD participants spent less time looking at the ROIs relative to the total time spent looking at the pictures (partial η2 = 0.10), and made fewer fixations on the ROIs (partial η2 = 0.16). Furthermore, visual scanning of the eye-ROI, but not the nose/mouth-ROI, predicted emotion recognition performance in the HD group, over and beyond general disease-related decline. Conclusion: The emotion recognition deficit in HD may partly be explained by general disease-related decline in cognition and motor functioning and partly by a social-emotional deficit, which is reflected in reduced eye-viewing. |
Quan Wang; Lauren DiNicola; Perrine Heymann; Michelle Hampson; Katarzyna Chawarska Impaired value learning for faces in preschoolers with Autism Spectrum Disorder Journal Article In: Journal of the American Academy of Child and Adolescent Psychiatry, vol. 57, no. 1, pp. 33–40, 2018. @article{Wang2018l, Objective One of the common findings in autism spectrum disorder (ASD) is limited selective attention toward social objects, such as faces. Evidence from both human and nonhuman primate studies suggests that selection of objects for processing is guided by the appraisal of object values. We hypothesized that impairments in selective attention in ASD may reflect a disruption of a system supporting learning about object values in the social domain. Method We examined value learning in social (faces) and nonsocial (fractals) domains in preschoolers with ASD (n = 25) and typically developing (TD) controls (n = 28), using a novel value learning task implemented on a gaze-contingent eye-tracking platform consisting of value learning and a selective attention choice test. Results Children with ASD performed more poorly than TD controls on the social value learning task, but both groups performed similarly on the nonsocial task. Within-group comparisons indicated that value learning in TD children was enhanced on the social compared to the nonsocial task, but no such enhancement was seen in children with ASD. Performance in the social and nonsocial conditions was correlated in the ASD but not in the TD group. Conclusion The study provides support for a domain-specific impairment in value learning for faces in ASD, and suggests that, in ASD, value learning in social and nonsocial domains may rely on a shared mechanism. These findings have implications both for models of selective social attention deficits in autism and for identification of novel treatment targets. |
Shuo Wang; Adam N. Mamelak; Ralph Adolphs; Ueli Rutishauser Encoding of target detection during visual search by single neurons in the human brain Journal Article In: Current Biology, vol. 28, pp. 2058–2069, 2018. @article{Wang2018f, Neurons in the primate medial temporal lobe (MTL) respond selectively to visual categories such as faces, contributing to how the brain represents stim- ulus meaning. However, it remains unknown whether MTL neurons continue to encode stimulus meaning when it changes flexibly as a function of variable task demands imposed by goal-directed behavior. While classically associated with long-term memory, recent lesion and neuroimaging studies show that the MTL also contributes critically to the online guid- ance of goal-directed behaviors such as visual search. Do such tasks modulate responses of neu-rons in the MTL, and if so, do their responses mirror bottom-up input from visual cortices or do they reflect more abstract goal-directed properties? To answer these questions, we performed concurrent recordings of eye movements and single neurons in the MTL and medial frontal cortex (MFC) in human neuro-surgical patients performing a memory-guided visual search task. We identified a distinct population of target-selective neurons in both the MTL and MFC whose response signaled whether the currently fixated stimulus was a target or distractor. This target-selective responsewas invariant to visual category and predicted whether a target was detected or missed behaviorally during a given fixation. The response latencies, relative to fixation onset, of MFC target-selective neurons preceded those in the MTL by ~200 ms, suggesting a frontal origin for the target signal. The human MTL thus represents not only fixed stimulus identity, but also task-specified stimulus relevance due to top-down goal relevance. |
Katharina S. Wehebrink; Katja Koelkebeck; Simon Piest; Carsten K. W. De Dreu; Mariska E. Kret Pupil mimicry and trust – Implication for depression Journal Article In: Journal of Psychiatric Research, vol. 97, no. 2018, pp. 70–76, 2018. @article{Wehebrink2018, Individuals suffering from depression often have difficulty trusting others. Previous research has shown a relationship between trust formation and pupil mimicry - the synchronization of pupil sizes between individuals. The current study therefore examined whether pupil mimicry is weaker in depressed individuals and an underlying factor of their low levels of trust. Forty-two patients with major depressive disorder (MDD) and 40 healthy control subjects played trust games with virtual partners. Images of these partners' eye regions were presented to participants before they had to make a monetary investment decision. Partners' pupils either dilated, constricted, or remained static over the course of 4-s interactions. During the task, participants' pupil sizes were recorded with eye-tracking equipment to assess mimicry. The results confirm that patients with MDD were somewhat less trusting than controls and used another's pupillary cues differently when deciding to trust. Specifically, whereas healthy controls trusted partners with dilating pupils more than partners with constricting pupils, patients with MDD particularly trusted partners whose pupils changed in size less, regardless of whether partners' pupils were dilating or constricting. This difference in investment behavior was unrelated to differences in pupil mimicry, which was equally apparent in both groups and fostered trust to the same extent. Whereas lower levels of trust observed in patients with MDD could not be explained by differences in pupil mimicry, our data show that pupil dilation mimicry might help people to trust. These findings provide further evidence for the important role of pupil size and pupil mimicry in interpersonal trust formation and shed light on the pathophysiology of clinically low trust in patients with MDD. |
Paul A. Wetzel; Anne S. Lindblad; Hardik Raizada; Nathan James; Caroline Mulatya; Mary A. Kannan; Zoe Villamar; George T. Gitchel; Lindell K. Weaver Eye tracking results in postconcussive syndrome versus normative participants Journal Article In: Investigative Ophthalmology & Visual Science, vol. 59, no. 10, pp. 4011–4019, 2018. @article{Wetzel2018, PURPOSE. Standard physical, neurologic, and neuropsychologic examinations may not detect abnormalities after mild traumatic brain injury (mTBI). An analysis of eye movements may be more sensitive to neurologic dysfunction. METHODS. We performed eye tracking assessments in 71 active duty and veteran military personnel with persistent postconcussive symptoms (3 months to 5 years after mTBI) and 75 volunteers with no history of brain injury. Both eyes were sampled at 500 Hz and analyzed for various eye measurement parameters during visual tasks involving the saccadic and smooth systems. RESULTS. No difference between mTBI and normal participants in main sequence profiles was observed. On the circular task, intersaccadic interval duration was shorter in mTBI compared with normal subjects (horizontal: Cohen's D = -0.65; vertical: Cohen's D = -0.75). For reading, absolute saccadic amplitudes (Cohen's D = -0.76) and average forward saccadic amplitudes were lower (Cohen's D= -0.61). Absolute fixation velocity was higher (Cohen's D = 1.02), and overall fixation durations (Cohen's D = 0.58), regression durations (Cohen's D = 0.49), and forward saccadic durations (Cohen's D = 0.54) were longer. mTBI participants had more fixations (Cohen's D = 0.54) and regressions per line (Cohen's D = 0.70) and read fewer lines (Cohen's D = -0.38) than normal subjects. On the horizontal ramp task, mTBI participants had lower weighted smooth pursuit gains (Cohen's D = -0.55). On the horizontal step task, mTBI participants had shorter mean fixation times (Cohen's D = -0.55). CONCLUSIONS. These results suggest vulnerability of the smooth pursuit and saccadic systems in mTBI. Eye tracking shows promise as an objective, sensitive assessment of damage after mTBI. |
Matthew B. Winn; Ashley N. Moore In: Trends in Hearing, vol. 22, 2018. @article{Winn2018, Contextual cues can be used to improve speech recognition, especially for people with hearing impairment. However, previous work has suggested that when the auditory signal is degraded, context might be used more slowly than when the signal is clear. This potentially puts the hearing-impaired listener in a dilemma of continuing to process the last sentence when the next sentence has already begun. This study measured the time course of the benefit of context using pupillary responses to high- and low-context sentences that were followed by silence or various auditory distractors (babble noise, ignored digits, or attended digits). Participants were listeners with cochlear implants or normal hearing using a 12-channel noise vocoder. Context-related differences in pupil dilation were greater for normal hearing than for cochlear implant listeners, even when scaled for differences in pupil reactivity. The benefit of context was systematically reduced for both groups by the presence of the later-occurring sounds, including virtually complete negation when sentences were followed by another attended utterance. These results challenge how we interpret the benefit of context in experiments that present just one utterance at a time. If a listener uses context to ‘‘repair'' part of a sentence, and later-occurring auditory stimuli interfere with that repair process, the benefit of context might not survive outside the idealized laboratory or clinical environment. Elevated listening effort in hearing-impaired listeners might therefore result not just from poor auditory encoding but also inefficient use of context and prolonged processing of misperceived utterances competing with perception of incoming speech. |
Yu Zhang; Aijuan Yan; Bingyu Liu; Ying Wan; Yuchen Zhao; Ying Liu; Jiangxiu Tan; Lu Song; Yong Gu; Zhenguo Liu Oculomotor performances are associated with motor and non-motor symptoms in Parkinson's disease Journal Article In: Frontiers in Neurology, vol. 9, pp. 960, 2018. @article{Zhang2018e, Background: Parkinson's disease (PD) patients exhibit deficits in oculomotor behavior, yet the results are inconsistent across studies. In addition, how these results are associated with clinical symptoms is unclear, especially in China. Methods: We designed a case-control study in China including 37 PD patients and 39 controls. Clinical manifestations in PD patients were recorded. Oculomotor performance was measured by a video-based eye tracker system. Results: We found that six oculomotor parameters, including fixation stability, saccadic latency, smooth pursuit gain, saccade frequency, viewing range, and saccade frequency during free-viewing context, were significantly different in PD patients and control group. Combining application of these six parameters could improve diagnostic accuracy to over 90%. Moreover, pursuit gain was significantly associated with PD duration, UPDRS III, in PD patients. Saccade latency was significantly associated with PD duration, Berg balance score, RBD score, and Total LEDD in PD patients. Conclusions: PD patients commonly exhibit oculomotor deficits in multiple behavioral contexts, which are associated with both motor and non-motor symptoms. Oculomotor test may provide a valuable tool for the clinical assessment of PD. |
Peng Zhou; Weiyi Ma; Likan Zhan; Huimin Ma Using the visual world paradigm to study sentence comprehension in Mandarin-speaking children with autism Journal Article In: Journal of Visualized Experiments, no. 140, pp. 1–8, 2018. @article{Zhou2018g, Sentence comprehension relies on the ability to rapidly integrate different types of linguistic and non-linguistic information. However, there is currently a paucity of research exploring how preschool children with autism understand sentences using different types of cues. The mechanisms underlying sentence comprehension remains largely unclear. The present study presents a protocol to examine the sentence comprehension abilities of preschool children with autism. More specifically, a visual world paradigm of eye-tracking is used to explore the moment-to-moment sentence comprehension in the children. The paradigm has multiple advantages. First, it is sensitive to the time course of sentence comprehension and thus can provide rich information about how sentence comprehension unfolds over time. Second, it requires minimal task and communication demands, so it is ideal for testing children with autism. To further minimize the computational burden of children, the present study measures eye movements that arise as automatic responses to linguistic input rather than measuring eye movements that accompany conscious responses to spoken instructions. |
Cedric Lamirel; Suzon Ajasse; Antoine Moulignier; Laurence Salomon; Romain Deschamps; Antoine Gueguen; Catherine Vignal; Isabelle Cochereau; Jean Lorenceau A novel method of inducing endogenous pupil oscillations to detect patients with unilateral optic neuritis Journal Article In: PLoS ONE, vol. 13, no. 8, pp. e0201730, 2018. @article{Lamirel2018, Purpose: To use and test a new method of inducing endogenously generated pupillary oscillations (POs) in patients with unilateral optic neuritis (ON), to describe a signal analysis approach quantifying pupil activity and to evaluate the extent to which POs permit to discriminate patients from control participants. Method: Pupil size was recorded with an eye-tracker and converted in real time to modulate the luminance of a stimulus (a 20˚ disk) presented in front of participants. With this biofeedback setting, an increasing pupil size transforms into a high luminance, entraining a pupil constriction that in turn decreases the stimulus luminance, and so on, resulting in endogenously generated POs. POs were recorded for 30 seconds in the affected eye, in the fellow eye and in binocular conditions with 22 patients having a history of unilateral ON within a period of 5 years, and with 22 control participants. Different signal analysis methods were used to quantify the power and frequency of POs. Results: On average, pupil size oscillated at around 1 Hz. The amplitude of POs appears not to be a reliable marker of ON. In contrast, the frequency of POs was significantly lower, and was more variable over time, in the patients' affected eye, as compared to their fellow eye and to the binocular condition. No such differences were found in control participants. Receiver operating characteristic analyses based on the frequency and the variability of POs to clas- sify patients and control participants gave an area under the curve of 0.82, a sensitivity of 82% (95%CI: 60%-95%) and a specificity of 77% (95%CI: 55%-92%). Conclusions: The new method used to induce POs allowed characterizing the visual afferent pathway defect in ON patients with encouraging accuracy. The method was fast, easy to use, only requiring that participants look ahead, and allows testing many stimulus parameters (e.g. color, stimulus location, size, etc). |
Stephanie J. Larcombe; Yuliya Kulyomina; Nikoleta Antonova; Sara Ajina; Charlotte J. Stagg; Philip L. Clatworthy; Holly Bridge Visual training in hemianopia alters neural activity in the absence of behavioural improvement: A pilot study Journal Article In: Ophthalmic and Physiological Optics, vol. 38, no. 5, pp. 538–549, 2018. @article{Larcombe2018a, BACKGROUND: Damage to the primary visual cortex (V1) due to stroke often results in permanent loss of sight affecting one side of the visual field (homonymous hemianopia). Some rehabilitation approaches have shown improvement in visual performance in the blind region, but require a significant time investment. METHODS: Seven patients with cortical damage performed 400 trials of a motion direction discrimination task daily for 5 days. Three patients received anodal transcranial direct current stimulation (tDCS) during training, three received sham stimulation and one had no stimulation. Each patient had an assessment of visual performance and a functional magnetic resonance imaging (fMRI) scan before and after training to measure changes in visual performance and cortical activity. RESULTS: No patients showed improvement in visual function due to the training protocol, and application of tDCS had no effect on visual performance. However, following training, the neural response in motion area hMT+ to a moving stimulus was altered. When the stimulus was presented to the sighted hemifield, activity decreased in hMT+ of the damaged hemisphere. There was no change in hMT+ response when the stimulus was presented to the impaired hemifield. There was a decrease in activity in the inferior precuneus after training when the stimulus was presented to either the impaired or sighted hemifield. Preliminary analysis of tDCS data suggested that anodal tDCS interacted with the delivered training, modulating the neural response in hMT+ in the healthy side of the brain. CONCLUSION: Training can affect the neural responses in hMT+ even in the absence of change in visual performance. |
Campbell Le Heron; Sanjay G. Manohar; Olivia Plant; Kinan Muhammed; Ludovica Griffanti; Andrea Nemeth; Gwenaëlle Douaud; Hugh S. Markus; Masud Husain Dysfunctional effort-based decision-making underlies apathy in genetic cerebral small vessel disease Journal Article In: Brain, vol. 141, pp. 3193–3210, 2018. @article{LeHeron2018, Apathy is a syndrome of reduced motivation that commonly occurs in patients with cerebral small vessel disease, including those with the early onset form, CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalo- pathy). The cognitive mechanisms underlying apathy are poorly understood and treatment options are limited. We hypothesized that disrupted effort-based decision-making, the cognitive process by which potential rewards and the effort cost required to obtain them is integrated to drive behaviour, might underlie the apathetic syndrome. Nineteen patients with a genetic diagnosis of CADASIL, as a model of ‘pure' vascular cognitive impairment, and 19 matched controls were assessed using two different behavioural paradigms and MRI. On a decision-making task, participants decided whether to accept or reject sequential offers of monetary reward in return for exerting physical effort via handheld dynamometers. Six levels of reward and six levels of effort were manipulated independently so offers spanned the full range of possible combinations. Choice, decision time and force metrics were recorded. Each participant's effort and reward sensitivity was estimated using a computational model of choice. On a separate eye movement paradigm, physiological reward sensitivity was indexed by measuring pupillary dilatation to increasing monetary incentives. This metric was related to apathy status and compared to the behavioural metric of reward sensitivity on the decision- making task. Finally, high quality diffusion imaging and tract-based spatial statistics were used to determine whether tracts linking brain regions implicated in effort-based decision-making were disrupted in apathetic patients. Overall, apathetic patients with CADASIL rejected significantly more offers on the decision-making task, due to reduced reward sensitivity rather than effort hypersensitivity. Apathy was also associated with blunted pupillary responses to incentives. Furthermore, these independent be- havioural and physiological markers of reward sensitivity were significantly correlated. Non-apathetic patients with CADASIL did not differ from controls on either task, whilst actual motor performance of apathetic patients in both tasks was also normal. Apathy was specifically associated with reduced fractional anisotropy within tracts connecting regions previously associated with effort-based decision-making. These findings demonstrate behavioural, physiological and anatomical evidence that dysfunctional effort-based decision-making underlies apathy in patients with CADASIL, a model disorder for sporadic small vessel disease. Reduced incentivization by rewards rather than hypersensitivity to effort costs drives this altered pattern of behaviour. The study provides empirical evidence of a cognitive mechanism for apathy in cerebral small vessel disease, and identifies a promising therapeutic target for interventions to improve this debilitating condition. |
Tak Hyung Lee; Taekwan Kim; Yoo Bin Kwak; Wu Jeong Hwang; Minah Kim; Jung-Seok Choi; Jun Soo Kwon Altered eye-movement patterns during text reading in obsessive–compulsive disorder and internet gaming disorder Journal Article In: Frontiers in Behavioral Neuroscience, vol. 12, pp. 248, 2018. @article{Lee2018a, Obsessive–compulsive disorder (OCD) and internet gaming disorder (IGD), which are similar in that both involve repetitive behaviors and related with cognitive dysfunctions, frequently begin in early adolescence, which is a critical period for learning. Although the deterioration in cognitive functioning caused by these conditions may have adverse effects on information processing, such as text reading, there has been no comprehensive research on the objective indicators of altered reading patterns in these patients. Therefore, we evaluated eye-movement patterns during text reading in patients with OCD or IGD. In total, 20 patients with OCD, 28 patients with IGD, and 24 healthy controls (HCs) participated in the reading task using an eye tracker. We compared the fixation durations, saccade amplitudes, and eye-movement regressions of the three groups during reading. We explored relationships between the parameters reflecting altered reading patterns and those reflecting the severity of clinical symptoms. The average fixation durations and forward saccade amplitudes did not differ significantly among the groups. There were more eye-movement regressions in patients with OCD than in patients with IGD and HCs. No correlation was found between altered eye-movement patterns during reading and the severity of clinical symptoms in any of the patient groups. The significantly increased number of regressions in the OCD group during reading may reflect these patients' difficulties with inferential information processing, whereas the reading pattern in the IGD group is relatively intact. These findings suggest that patients with OCD and patients with IGD have different eye-movement patterns during reading reflecting distinct cognitive impairments in the two patient groups. |
Chi-Wen Liang Attentional control deficits in social anxiety: Investigating inhibition and shifting functions using a mixed antisaccade paradigm Journal Article In: Journal of Behavior Therapy and Experimental Psychiatry, vol. 60, pp. 46–52, 2018. @article{Liang2018, Background and objectives: Attentional control has recently been assumed to play a critical role in the generation and maintenance of threat-related attentional bias and social anxiety. The present study aimed to investigate whether socially anxious (SA) individuals show impairments in attentional control functions, particularly in inhibition and shifting. Methods: Forty-two SA and 41 non-anxious (NA) participants completed a mixed antisaccade task, a variant of the antisaccade task that is used to investigate inhibition as well as shifting functions. Results: The results showed that, overall, SA participants had longer antisaccade latencies than NA participants, but the two groups did not differ in their antisaccade error rates. Moreover, in the single-task block, SA participants had longer latencies than NA participants for antisaccade but not prosaccade trials. In the mixed-task block, the SA participants had longer latencies than the NA participants for both task types. The two groups did not differ in their latency switch costs in the mixed-task blocks. Limitations: First, this study was conducted using a non-clinical sample of undergraduate students. Second, the antisaccade task measures primarily oculomotor inhibition. Third, this study did not include the measure of state anxiety to rule out the effects of state anxiety on the present findings. Conclusions: This study suggests that SA individuals demonstrate diminished efficiency of inhibition function but show no significant impairment of shifting function. However, in the mixed-task condition, SA individuals may exhibit an overall reduction in processing efficiency due to the higher task difficulty. |
Amy M. Lieberman; Arielle Borovsky; Rachel I. Mayberry Prediction in a visual language: Real-time sentence processing in American Sign Language across development Journal Article In: Language, Cognition and Neuroscience, vol. 33, no. 4, pp. 387–401, 2018. @article{Lieberman2018, Prediction during sign language comprehension may enable signers to integrate linguistic and non-linguistic information within the visual modality. In two eye-tracking experiments, we investigated American Sign language (ASL) semantic prediction in deaf adults and children (aged 4–8 years). Participants viewed ASL sentences in a visual world paradigm in which the sentence-initial verb was either neutral or constrained relative to the sentence-final target noun. Adults and children made anticipatory looks to the target picture before the onset of the target noun in the constrained condition only, showing evidence for semantic prediction. Crucially, signers alternated gaze between the stimulus sign and the target picture only when the sentential object could be predicted from the verb. Signers therefore engage in prediction by optimising visual attention between divided linguistic and referential signals. These patterns suggest that prediction is a modality-independent process, and theoretical implications are discussed. |
Ebony R. Lindor; Nicole J. Rinehart; Joanne Fielding Superior visual search and crowding abilities are not characteristic of all individuals on the autism spectrum Journal Article In: Journal of Autism and Developmental Disorders, vol. 48, pp. 3499–3512, 2018. @article{Lindor2018, Individuals with Autism Spectrum Disorder (ASD) often excel on visual search and crowding tasks; however, inconsistent findings suggest that this 'islet of ability' may not be characteristic of the entire spectrum. We examined whether performance on these tasks changed as a function of motor proficiency in children with varying levels of ASD symptomology. Children with high ASD symptomology outperformed all others on complex visual search tasks, but only if their motor skills were rated at, or above, age expectations. For the visual crowding task, children with high ASD symptomology and superior motor skills exhibited enhanced target discrimination, whereas those with high ASD symptomology but poor motor skills experienced deficits. These findings may resolve some of the discrepancies in the literature. |
Jiachen Liu; Yifeng Zhou; Tzvetomir Tzvetanov Globally normal bistable motion perception of Anisometropic amblyopes may profit from an unusual coding mechanism Journal Article In: Frontiers in Neuroscience, vol. 12, pp. 391, 2018. @article{Liu2018h, Anisometropic amblyopia is a neurodevelopmental disorder of the visual system. There is evidence that the neural deficits spread across visual areas, from the primary cortex up to higher brain areas, including motion coding structures such as MT. Here, we used bistable plaid motion to investigate changes in the underlying mechanisms of motion integration and segmentation and, thus, help us to unravel in more detail deficits in the amblyopic visual motion system. Our results showed that 1) amblyopes globally exhibited normal bistable perception in all viewing conditions compared to the control group and 2) decreased contrast led to a stronger increase in percept switches and decreased percept durations in the control group, while the amblyopic group exhibited no such changes. There were few differences in outcomes dependent upon the use of the weak eye, the strong eye, or both eyes for viewing the stimuli, but this was a general effect present across all subjects, not specific to the amblyopic group. To understand the role of noise and adaptation in such cases of bistable perception, we analysed predictions from a model and found that contrast does indeed affect percept switches and durations as observed in the control group, in line with the hypothesis that lower stimulus contrast enhances internal noise effects. The combination of experimental and computational results presented here suggests a different motion coding mechanism in the amblyopic visual system, with relatively little effect of stimulus contrast on amblyopes' bistable motion perception. |
Qilin Lu; Xiaoxiao Wang; Lin Li; Bensheng Qiu; Shihui Wei; Bernhard A. Sabel; Yifeng Zhou Visual rehabilitation training alters attentional networks in hemianopia: An fMRI study Journal Article In: Clinical Neurophysiology, vol. 129, no. 9, pp. 1832–1841, 2018. @article{Lu2018c, Objective: Hemianopia is a visual field defect following post-chiasmatic damage. We now applied functional magnetic resonance imaging (fMRI) in hemianopic patients before and after visual rehabilitation training (VRT) to examine the impact of VRT on attentional function networks. Methods: Seven chronic hemianopic patients with post- chiasmatic lesions carried out a VRT for five weeks under fixation control. Before vs. after intervention, we assessed the area of residual vision (ARV), contrast sensitivity function (CSF) and functional MRI data and correlated them with each other. Results: VRT significantly improved the visual function of grating detection at the training location. Using fMRI, we found that the training led to a strengthening of connectivity between the right temporoparietal junction (rTPJ) to the insula and the anterior cingulate cortex (ACC), all of which belong to the cortical attentional network. However, no significant correlation between alterations of brain activity and improvements of either CSF or ARV was found. Conclusion: Visual rehabilitation training partially restored the deficient visual field sectors and could improve attentional network function in hemianopia. Significance: Our MRI results highlight the role of attention and the rTPJ activation as one, but not the only, component of VRT in hemianopia. |
Manuela Malaspina; Andrea Albonico; Junpeng Lao; Roberto Caldara; Roberta Daini Mapping self-face recognition strategies in congenital prosopagnosia Journal Article In: Neuropsychology, vol. 32, no. 2, pp. 123–137, 2018. @article{Malaspina2018, OBJECTIVE: Recent evidence showed that individuals with congenital face processing impairment (congenital prosopagnosia [CP]) are highly accurate when they have to recognize their own face (self-face advantage) in an implicit matching task, with a preference for the right-half of the self-face (right perceptual bias). Yet the perceptual strategies underlying this advantage are unclear. Here, we aimed to verify whether both the self-face advantage and the right perceptual bias emerge in an explicit task, and whether those effects are linked to a different scanning strategy between the self-face and unfamiliar faces. METHOD: Eye movements were recorded from 7 CPs and 13 controls, during a self/other discrimination task of stimuli depicting the self-face and another unfamiliar face, presented upright and inverted. RESULTS: Individuals with CP and controls differed significantly in how they explored faces. In particular, compared with controls, CPs used a distinct eye movement sampling strategy for processing inverted faces, by deploying significantly more fixations toward the nose and mouth areas, which resulted in more efficient recognition. Moreover, the results confirmed the presence of a self-face advantage in both groups, but the eye movement analyses failed to reveal any differences in the exploration of the self-face compared with the unfamiliar face. Finally, no bias toward the right-half of the self-face was found. CONCLUSIONS: Our data suggest that the self-face advantage emerges both in implicit and explicit recognition tasks in CPs as much as in good recognizers, and it is not linked to any specific visual exploration strategies. |
N. A. Martin-Key; Erich W. Graf; W. J. Adams; G. Fairchild Facial emotion recognition and eye movement behaviour in conduct disorder Journal Article In: Journal of Child Psychology and Psychiatry, vol. 59, no. 3, pp. 247–257, 2018. @article{MartinKey2018, Background: Conduct Disorder (CD) is associated with impairments in facial emotion recognition. However, it is unclear whether such deficits are explained by a failure to attend to emotionally informative face regions, such as the eyes, or by problems in the appraisal of emotional cues. Method: Male and female adolescents with CD and varying levels of callous-unemotional (CU) traits and age- and sex-matched typically developing (TD) controls (aged 13–18) categorised the emotion of dynamic and morphed static faces. Concurrent eye tracking was used to relate categorisation performance to participants' allocation of overt attention. Results: Adolescents with CD were worse at emotion recognition than TD controls, with deficits observed across static and dynamic expressions. In addition, the CD group fixated less on the eyes when viewing fearful and sad expressions. Across all participants, higher levels of CU traits were associated with fear recognition deficits and reduced attention to the eyes of surprised faces. Within the CD group, however, higher CU traits were associated with better fear recognition. Overall, males were worse at recognising emotions than females and displayed a reduced tendency to fixate the eyes. Discussion: Adolescents with CD, and particularly males, showed deficits in emotion recognition and fixated less on the eyes when viewing emotional faces. Individual differences in fixation behaviour predicted modest variations in emotion categorisation. However, group differences in fixation were small and did not explain the much larger group differences in categorisation performance, suggesting that CD-related deficits in emotion recognition were not mediated by abnormal fixation patterns. |
Aditi Subramaniam; Vijay Danivas; Sri Mahavir Agarwal; Sunil Kalmady; Venkataram Shivakumar; Anekal C. Amaresha; Anushree Bose; Janardhanan C. Narayanaswamy; Shivarama Varambally; Samuel B. Hutton; Ganesan Venkatasubramanian; Bangalore N. Gangadhar Clinical correlates of saccadic eye movement in antipsychotic-naïve schizophrenia Journal Article In: Psychiatry Research, vol. 259, pp. 154–159, 2018. @article{Subramaniam2018, Some aspects of saccadic performance have been found to be abnormal in chronic schizophrenia. The majority of this research has, however, been performed on patients treated with long-term antipsychotic medication. Very few studies have examined saccadic performance in antipsychotic-naïve/free patients. There are also very few studies describing the relationship between saccadic performance and clinical symptoms, particularly in antipsychotic free patients. In this study, we compared pro and antisaccade performance in a large sample of antipsychotic-naïve/free schizophrenia patients (N = 45) with healthy controls (N = 57). Clinical symptoms were assessed using Scale for Assessment of Positive Symptoms (SAPS) and Negative Symptoms (SANS). In the antisaccade task, patients made significantly more errors, and their correct antisaccades had smaller amplitudes in comparison to healthy controls. Higher error rates were associated with increased severity of hallucinations. In the prosaccade task, patients had less accurate final eye positions, and made saccades with slower latency and reduced amplitude compared to the healthy controls. These observations in schizophrenia patients without the potential confounds of antipsychotic treatment suggest intrinsic link between saccadic deficits and schizophrenia pathogenesis. The relationship between antisaccade errors and hallucination severity supports the potential link between hallucinations and deficits in inhibitory control. |
Emma Sumner; Samuel B. Hutton; Gustav Kuhn; Elisabeth L. Hill Oculomotor atypicalities in developmental coordination disorder Journal Article In: Developmental Science, vol. 21, no. 1, pp. 1–12, 2018. @article{Sumner2018a, Children with Developmental Coordination Disorder (DCD) fail to acquire adequate motor skill, yet surprisingly little is known about the oculomotor system in DCD. Successful completion of motor tasks is supported by accurate visual feedback. The purpose of this study was to determine whether any oculomotor differences can distinguish between children with and without a motor impairment. Using eye tracking technology, visual fixation, smooth pursuit, and pro- and anti-saccade performance were assessed in 77 children that formed three groups: children with DCD (aged 7-10), chronologically age (CA) matched peers, and a motor-match (MM) group (aged 4-7). Pursuit gain and response preparation in the pro- and anti-saccade tasks were comparable across groups. Compared to age controls, children with DCD had deficits in maintaining engagement in the fixation and pursuit tasks, and made more anti-saccade errors. The two typically developing groups performed similarly, except on the fast speed smooth pursuit and antisaccade tasks, where the CA group outperformed the younger MM group. The findings suggest that children with DCD have problems with saccadic inhibition and maintaining attention on a visual target. Developmental patterns were evident in the typically developing groups, suggesting that the pursuit system and cognitive control develop with age. This study adds to the literature by being the first to systematically identify specific oculomotor differences between children with and without a motor impairment. Further examination of oculomotor control may help to identify underlying processes contributing to DCD. |
Emma Sumner; Hayley C. Leonard; Elisabeth L. Hill Comparing attention to socially-relevant stimuli in autism spectrum disorder and developmental coordination disorder Journal Article In: Journal of Abnormal Child Psychology, vol. 46, no. 8, pp. 1717–1729, 2018. @article{Sumner2018, Difficulties with social interaction have been reported in both children with an autism spectrum disorder (ASD) and children with developmental coordination disorder (DCD), although these disorders have very different diagnostic characteristics. To date, assessment of social skills in a DCD population has been limited to paper-based assessment or parent report. The present study employed eye tracking methodology to examine how children attend to socially-relevant stimuli, comparing 28 children with DCD, 28 children with ASD and 26 typically-developing (TD) age-matched controls (aged 7-10). Eye movements were recorded while children viewed 30 images, half of which were classed as 'Individual' (one person in the scene, direct gaze) and the other half were 'Social' (more naturalistic scenes showing an interaction). Children with ASD spent significantly less time looking at the face/eye regions in the images than TD children, but children with DCD performed between the ASD and TD groups in this respect. Children with DCD demonstrated a reduced tendency to follow gaze, in comparison to the ASD group. Our findings confirm that social atypicalities are present in both ASD and to a lesser extent DCD, but follow a different pattern. Future research would benefit from considering the developmental nature of the observed findings and their implications for support. |
Ayuko Suzuki; Jun Shinozaki; Shogo Yazawa; Yoshino Ueki; Noriyuki Matsukawa; Shun Shimohama; Takashi Nagamine In: Journal of Alzheimer's Disease, vol. 61, no. 4, pp. 1653–1665, 2018. @article{Suzuki2018, Background: The mental rotation task is well-known for the assessment of visuospatial function; however, it has not been used for screening of dementia patients. Objective: The aim of this study was to create a simple screening test for patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) by focusing on non-amnestic symptoms. Methods: Age-matched healthy controls (age 75.3+/-6.8), patients with MCI (76.5+/-5.5), and AD (78.2+/-5.0) participated in this study. They carried out mental rotation tasks targeting geometric graphics or alphabetical characters with three rotating angles (0degree, 90degree, and 180degree) and indicated the correct answer. Response accuracy and reaction time were recorded along with their eye movements using an eye tracker. To quantify their visual processing strategy, the run count ratio (RC ratio) was calculated by dividing the mean number of fixations in incorrect answers by that in correct answers. Results: AD patients showed lower accuracy and longer reaction time than controls. They also showed a significantly greater number of fixation and smaller saccade amplitude than controls, while fixation duration did not differ significantly. The RC ratio was higher for AD, followed by MCI and control groups. By setting the cut-off value to 0.47 in the 180degree rotating angle task, we could differentiate MCI patients from controls with a probability of 80.0%. Conclusions: We established a new screening system for dementia patients by evaluating visuospatial function. The RC ratio during a mental rotation task is useful for discriminating MCI patients from controls. |
Katharine N. Thakkar; Kassidy Fifer; Jan W. Brascamp; Sohee Park; Livon Ghermezi; Jeffrey D. Schall Reduced pupil dilation during action preparation in schizophrenia Journal Article In: International Journal of Psychophysiology, vol. 128, pp. 111–118, 2018. @article{Thakkar2018, Impairments in cognitive control—the ability to exert control over thoughts and actions and respond flexibly to the environment—are well-documented in schizophrenia. However, the degree to which experimental task performance reflects true cognitive control impairments or more general alterations in effort, arousal and/or task preparedness is unclear. Pupillary responses can provide insight into these latter factors, as the pupil dilates with degree of cognitive effort and response preparation. In the current study, 16 medicated outpatients with schi- zophrenia (SZP) and 18 healthy controls performed a task that measures the ability to reactively inhibit and modify a planned action—the double-step task. In this task, participants were required to make a saccade to a visual target. Infrequently, the target jumped to a new location and participants were instructed to rapidly inhibit and change their eye movement plan. Applying a race model of performance, we have previously shown that SZP require more time to inhibit a planned action. In the current analysis, we measured pupil dilation associated with task preparation and found that SZP had a shallower increase in pupil size prior to the onset of the trial. Additionally, reduced magnitude of the pupil response was associated with negative symptom severity in patients. Based on primate neurophysiology and cognitive neuroscience work, we suggest that this blunted pupillary response may reflect abnormalities in a general orienting response or reduced motivational sig- nificance of a cue signifying the onset of a preparatory period and that these abnormalities might share an autonomic basis with negative symptoms. |
Maria Theodorou; Ana Quartilho; Wen Xing; Catey Bunce; Gary S. Rubin; Gillian Adams; Annegret Dahlmann-Noor Soft contact lenses to optimize vision in adults with idiopathic infantile nystagmus: A pilot parallel randomized controlled trial Journal Article In: Strabismus, vol. 26, no. 1, pp. 11–21, 2018. @article{Theodorou2018, Purpose: The optimal management of infantile nystagmus syndrome (INS) is still unclear. Contact lenses (CL) may be superior to glasses in improving visual function in INS but it is not known whether their beneficial effects are due to optical correction alone, or to an additional proprio- ceptive effect, and whether soft CLs would be as effective as rigid CLs. There is little data on feasibility and and the present study aimed to provide this information. Methods: We completed a pilot Randomized Control Trial (RCT) at a single tertiary referral centre in London, UK. We enrolled 38 adults with idiopathic INS and randomised them to either plano CL (with corrective spectacles if required) or to corrective CL. CL wear was required for a minimum of 2 weeks. Primary outcome measures were feasibility and safety of CL wear in INS; secondary outcome measures were visual acuity and nystagmus waveform parameters. Results: 27 completed the study (27/38,71%). 4 partcipants withdrew due to difficulty with CL insertion/ removal and 7were lost to follow up. CL tolerability was high (24/27,89%) - 2 found the CLs irritant, and 1 had an exacerbation of allergic eye disease. At two weeks, mean improvement in binocular visual acuity from baseline with plano CLs was 0.07 logMAR (95% confidence interval (CI: 0.03-0.11) and 0.06 logMAR with fully corrective CLs (95% CI:0.02-0.1). Mean improvement in the eXpanded Nystagmus Acuity Function (NAFX, a nystagmus acuity function based on eye movement recording) with plano CLs was -0.04(95% CI: -0.08-0.005) and -0.05 with fully corrective CLs(95% CI: -0.09–0.003). Conclusions: CLs are well tolerated, with a low risk profile. Whilst our study was not powered to detect significant changes in BCVA and waveform parameters between treatment arms, we observed a trend towards an improvement in visual function at two weeks from baseline with CLs. |
Grace Anne Thompson; Larry Allen Abel Fostering spontaneous visual attention in children on the autism spectrum: A proof-of-concept study comparing singing and speech Journal Article In: Autism Research, vol. 11, no. 5, pp. 732–737, 2018. @article{Thompson2018, Children on the autism spectrum are reported to have lower rates of social gaze as early as toddlerhood, and this pattern persists across the lifespan. Finding ways to promote more natural and spontaneous engagement in social interactions may help to boost developmental opportunities in the child's home and community settings. This proof-of-concept study hypothesized that a video of a singer would elicit more attention to the performer, particularly to her face, than a video of her reading a story, and that the child's familiarity with the material would enhance attention. Sixteen children on the autism spectrum (7-10 years old) watched 4 videos 1 min long comprising a favorite song or story, and an unfamiliar song and story. Eye movements were recorded, and three-way repeated measures ANOVAs examined the proportion of total valid visual dwell time and fixations, in each trial and each target area. For proportion of both dwell time and fixation counts, children were significantly more likely to look at the performer's face and body and less at the prop during singing than story-telling and when familiar rather than unfamiliar material was presented. These findings raise important issues for supporting children to naturally initiate looking toward a person's face. |
Steven M. Thurman; Marcello Maniglia; Pinakin G. Davey; Mandy K. Biles; Kristina M. Visscher; Aaron R. Seitz Multi-line adaptive perimetry (MAP): A new procedure for quantifying visual field integrity for rapid assessment of macular diseases Journal Article In: Translational Vision Science & Technology, vol. 7, no. 5, pp. 1–18, 2018. @article{Thurman2018, Purpose: In order to monitor visual defects associated with macular degeneration (MD), we present a new psychophysical assessment called multiline adaptive perimetry (MAP) that measures visual field integrity by simultaneously estimating regions associated with perceptual distortions (metamorphopsia) and visual sensitivity loss (scotoma). Methods: We first ran simulations of MAP with a computerized model of a human observer to determine optimal test design characteristics. In experiment 1, predictions of the model were assessed by simulating metamorphopsia with an eye-tracking device with 20 healthy vision participants. In experiment 2, eight patients (16 eyes) with macular disease completed two MAP assessments separated by about 12 weeks, while a subset (10 eyes) also completed repeated Macular Integrity Assessment (MAIA) microperimetry and Amsler grid exams. Results: Results revealed strong repeatability of MAP and high accuracy, sensitivity, and specificity (0.89, 0.81, and 0.90, respectively) in classifying patient eyes with severe visual impairment. We also found a significant relationship in terms of the spatial patterns of performance across visual field loci derived from MAP and MAIA microperimetry. However, there was a lack of correspondence between MAP and subjective Amsler grid reports in isolating perceptually distorted regions. Conclusions: These results highlight the validity and efficacy of MAP in producing quantitative maps of visual field disturbances, including simultaneous mapping of metamorphopsia and sensitivity impairment. Translational Relevance: Future work will be needed to assess applicability of this examination for potential early detection of MD symptoms and/or portable assessment on a home device or computer. |
Leah N. Tobin; Christopher R. Sears; Alicia S. Zumbusch; Kristin M. Von Ranson Attention to fat- and thin-related words in body-satisfied and body-dissatisfied women before and after thin model priming Journal Article In: PLoS ONE, vol. 13, no. 2, pp. e0192914, 2018. @article{Tobin2018, Understanding the cognitive processes underlying body dissatisfaction provides important information on the development and perpetuation of eating pathology. Previous research suggests that body-dissatisfied women process weight-related information differently than body-satisfied women, but the precise nature of these processing differences is not yet understood. In this study, eye-gaze tracking was used to measure attention to weight-related words in body-dissatisfied (n = 40) and body-satisfied (n = 38) women, before and after exposure to images of thin fashion models. Participants viewed 8-second displays containing fat-related, thin-related, and neutral words while their eye fixations were tracked and recorded. Based on previous research and theory, we predicted that body-dissatisfied women would attend to fat-related words more than body-satisfied women and would attend to thin-related words less. It was also predicted that exposure to thin model images would increase self-rated body dissatisfaction and heighten group differences in attention. The results indicated that body-dissatisfied women attended to both fat- and thin-related words more than body-satisfied women and that exposure to thin models did not increase this effect. Implications for cognitive models of eating disorders are discussed. |
Shin-ichi Tokushige; Shun-ichi Matsuda; Genko Oyama; Yasushi Shimo; Atsushi Umemura; Takuya Sasaki; Satomi Inomata-Terada; Akihiro Yugeta; Masashi Hamada; Yoshikazu Ugawa; Shoji Tsuji; Nobutaka Hattori; Yasuo Terao Effect of subthalamic nucleus deep brain stimulation on visual scanning Journal Article In: Clinical Neurophysiology, vol. 129, no. 11, pp. 2421–2432, 2018. @article{Tokushige2018, Objective: Deep brain stimulation (DBS) can provide insights into the workings of the basal ganglia (BG) by interfering with their function. In patients with Parkinson's disease (PD) treated with DBS of the subthalamic nucleus, we studied the effect of DBS on scanning eye movements. Methods: In the visual memory task, subjects viewed images of various complexities for later recall. In visual search tasks, subjects looked for and fixated one odd target ring, embedded among 48 Landolt rings, which either stood out or not from the distractors. We compared the parameters of scanning saccades when DBS was on and off. Results: In the visual memory task, DBS increased the amplitude of saccades scanning simple but not complex drawings. In the visual search tasks, DBS showed no effect on saccade amplitude or frequency. Conclusions: Saccades when viewing simple images were affected by DBS since they are internally guided saccades, for which the involvement of BG is large. In contrast, saccades when viewing complex images or during visual search, made with the help of visual cues in the images (externally guided saccades) and less dependent on BG, were resistant to the effect of DBS. Significance: DBS affects saccades differentially depending on the task. |
Inna Tsirlin; Linda Colpa; Herbert C. Goltz; Agnes M. F. Wong Visual search deficits in amblyopia Journal Article In: Journal of Vision, vol. 18, no. 4, pp. 1–16, 2018. @article{Tsirlin2018, Amblyopia is a neurodevelopmental disorder defined as a reduction in visual acuity that cannot be corrected by optical means. It has been associated with low-level deficits. However, research has demonstrated a link between amblyopia and visual attention deficits in counting, tracking, and identifying objects. Visual search is a useful tool for assessing visual attention but has not been well studied in amblyopia. Here, we assessed the extent of visual search deficits in amblyopia using feature and conjunction search tasks. We compared the performance of participants with amblyopia (n = 10) to those of controls (n = 12) on both feature and conjunction search tasks using Gabor patch stimuli, varying spatial bandwidth and orientation. To account for the low-level deficits inherent in amblyopia, we measured individual contrast and crowding thresholds and monitored eye movements. The display elements were then presented at suprathreshold levels to ensure that visibility was equalized across groups. There was no performance difference between groups on feature search, indicating that our experimental design controlled successfully for low-level amblyopia deficits. In contrast, during conjunction search, median reaction times and reaction time slopes were significantly larger in participants with amblyopia compared with controls. Amblyopia differentially affects performance on conjunction visual search, a more difficult task that requires feature binding and possibly the involvement of higher-level attention processes. Deficits in visual search may affect day-to-day functioning in people with amblyopia. |
Marco Turi; David C. Burr; Paola Binda Pupillometry reveals perceptual differences that are tightly linked to autistic traits in typical adults Journal Article In: eLife, vol. 7, pp. 1–15, 2018. @article{Turi2018, The pupil is primarily regulated by prevailing light levels but is also modulated by perceptual and attentional factors. We measured pupil-size in typical adult humans viewing a bistable-rotating cylinder, constructed so the luminance of the front surface changes with perceived direction of rotation. In some participants, pupil diameter oscillated in phase with the ambiguous perception, more dilated when the black surface was in front. Importantly, the magnitude of oscillation predicts autistic traits of participants, assessed by the Autism-Spectrum Quotient AQ. Further experiments suggest that these results are driven by differences in perceptual styles: high AQ participants focus on the front surface of the rotating cylinder, while those with low AQ distribute attention to both surfaces in a more global, holistic style. This is the first evidence that pupillometry reliably tracks inter-individual differences in perceptual styles; it does so quickly and objectively, without interfering with spontaneous perceptual strategies. |
Koen Lith; Dick Johan Veltman; Moran Daniel Cohn; Louise Else Pape; Marieke Eleonora Akker-Nijdam; Amanda Wilhelmina Geertruida Loon; Pierre Bet; Guido Alexander Wingen; Wim Brink; Theo Doreleijers; Arne Popma Effects of methylphenidate during fear learning in antisocial adolescents: A randomized controlled fMRI trial Journal Article In: Journal of the American Academy of Child and Adolescent Psychiatry, vol. 57, no. 12, pp. 934–943, 2018. @article{Lith2018, Objective: Although the neural underpinnings of antisocial behavior have been studied extensively, research on pharmacologic interventions targeting specific neural mechanisms remains sparse. Hypoactivity of the amygdala and ventromedial prefrontal cortex (vmPFC) has been reported in antisocial adolescents, which could account for deficits in fear learning (amygdala) and impairments in decision making (vmPFC), respectively. Limited clinical research suggests positive effects of methylphenidate, a dopamine agonist, on antisocial behavior in adolescents. Dopamine is a key neurotransmitter involved in amygdala and vmPFC functioning. The objective of this study was to investigate whether methylphenidate targets dysfunctions in these brain areas in adolescents with antisocial behavior. Method: A group of 42 clinical referred male adolescents (14–17 years old) with a disruptive behavior disorder performed a fear learning/reversal paradigm in a randomized double-blinded placebo-controlled pharmacologic functional magnetic resonance imaging study. Participants with disruptive behavior disorder were randomized to receive a single dose of methylphenidate 0.3 to 0.4 mg/kg (n = 22) or placebo (n = 20) and were compared with 21 matched healthy controls not receiving medication. Results: In a region-of-interest analysis of functional magnetic resonance imaging data during fear learning, the placebo group showed hyporeactivity of the amygdala compared with healthy controls, whereas amygdala reactivity was normalized in the methylphenidate group. There were no group differences in vmPFC reactivity during fear reversal learning. Whole-brain analyses showed no group differences. Conclusion: These findings suggest that methylphenidate is a promising pharmacologic intervention for youth antisocial behavior that could restore amygdala functioning. |
Stuart Wallis; Yit Yang; Stephen J. Anderson Word Mode: A crowding-free reading protocol for individuals with macular disease Journal Article In: Scientific Reports, vol. 8, pp. 1241, 2018. @article{Wallis2018, Central retinal loss through macular disease markedly reduces the ability to read largely because identification of a word using peripheral vision is negatively influenced by nearby text, a phenomenon termed visual crowding. Here, we present a novel peripheral reading protocol, termed Word Mode, that eliminates crowding by presenting each word in isolation but in a position that mimics its natural position in the line of text being read, with each new word elicited using a self-paced button press. We used a gaze-contingent paradigm to simulate a central scotoma in four normally-sighted observers, and measured oral reading speed for text positioned 7.5° in the inferior field. Compared with reading whole sentences, our crowding-free protocol increased peripheral reading speeds by up to a factor of seven, resulted in significantly fewer reading errors and fixations per sentence, and reduced both the critical print size and the text size required for spot reading by 0.2–0.3 logMAR. We conclude that the level of reading efficiency afforded by the crowding-free reading protocol Word Mode may return reading as a viable activity to many individuals with macular disease. |
Ricardo Ramos Gameiro; Kristin Jünemann; Anne Herbik; Anika Wolff; Peter König; Michael B. Hoffmann Natural visual behavior in individuals with peripheral visual-field loss Journal Article In: Journal of Vision, vol. 18, no. 12, pp. 1–21, 2018. @article{Gameiro2018, Retinitis pigmentosa (RP) is an inherited disease that causes progressive peripheral visual-field loss. In this study, we investigated how such loss affects visual exploration of natural images. Individuals with varying degrees of visual-field loss and healthy control participants freely observed images of different sizes while eye movements were recorded. We examined whether visual behavior differed when the scene content was shown in various extents of the visual field, and investigated the spatial bias, saccade amplitudes, and number and duration of fixations. We found that the healthy control group showed a central spatial bias during image viewing. The RP group showed similar biases on the group level, but with reproducible individual exploration patterns. For saccade amplitudes, the healthy control group and the RP group showed similar behavior throughout all image sizes. The RP group with severe loss of peripheral vision thus tended to target saccades toward blind areas of their visual field. The number of fixations did not change between the two groups, although fixation durations decreased in the RP group. In conclusion, the RP group scanned the images surprisingly similarly to the healthy control group; however, they showed individual idiosyncratic explorative strategies when the observed scene exceeded their visible field. Thus, although RP leads to a severe loss of the visual field, there is no general adaptive mechanism to change visual exploration. Instead, individuals rely on individual strategies, leading to high heterogeneity in the RP group. |
Melanie Gangl; Kristina Moll; Manon W. Jones; Chiara Banfi; Gerd Schulte-Körne; Karin Landerl Lexical reading in dysfluent readers of German Journal Article In: Scientific Studies of Reading, vol. 22, no. 1, pp. 24–40, 2018. @article{Gangl2018a, Dyslexia in consistent orthographies like German is characterized by dysfluent reading, which is often assumed to result from failure to build up an orthographic lexicon and overreliance on decoding. However, earlier evidence indicates effects of lexical processing at least in some German dyslexic readers. We investigated variations in reading style in an eye-tracking paradigm with German dysfluent 3rd and 4th graders. Twenty-six TypFix-readers (fixation counts within the range of 47 age-matched typical readers) were compared with 42 HighFix-readers (increased fixation counts). Both groups showed lexical access: Words were read more efficiently than nonwords and pseudohomophones. TypFix-readers showed stronger reliance on lexical reading than HighFix-readers (smaller length effects for number of fixations and total reading time, stronger lexicality effects for gaze duration, stronger word-pseudohomophone effects for mean saccade amplitude). We conclude that in both groups, sublexical and lexical reading processes were impaired due to inefficient visual-verbal integration. |
Fatema F. Ghasia; Jorge Otero-Millan; Aasef G. Shaikh Abnormal fixational eye movements in strabismus Journal Article In: British Journal of Ophthalmology, vol. 102, no. 2, pp. 253–259, 2018. @article{Ghasia2018, Introduction: Fixational saccades are miniature eye movements that constantly change the gaze during attempted visual fixation. Visually guided saccades and fixational saccades represent an oculomotor continuum and are produced by common neural machinery. Patients with strabismus have disconjugate binocular horizontal saccades. We examined the stability and variability of eye position during fixation in patients with strabismus and correlated the severity of fixational instability with strabismus angle and binocular vision. Methods: Eye movements were measured in 13 patients with strabismus and 16 controls during fixation and visually guided saccades under monocular viewing conditions. Fixational saccades and intersaccadic drifts were analysed in the viewing and non-viewing eye of patients with strabismus and controls. Results: We found an increase in fixational instability in patients with strabismus compared with controls. We also found an increase in the disconjugacy of fixational saccades and intrasaccadic ocular drift in patients with strabismus compared with controls. The disconjugacy was worse in patients with large-angle strabismus and absent stereopsis. There was an increase in eye position variance during drifts in patients with strabismus. Our findings suggest that both fixational saccades and intersaccadic drifts are abnormal and likely contribute to the fixational instability in patients with strabismus. Discussion: Fixational instability could be a useful tool for mass screenings of children to diagnose strabismus in the absence of amblyopia and latent nystagmus. The increased disconjugacy of fixational eye movements and visually guided saccades in patients with strabismus reflects the disruption of the fine-tuning of the motor and visual systems responsible for achieving binocular fusion in these patients. |
Julia Habicht; Mareike Finke; Tobias Neher Auditory acclimatization to bilateral hearing aids: Effects on sentence-in-noise processing times and speech-evoked potentials Journal Article In: Ear & Hearing, vol. 39, no. 1, pp. 161–171, 2018. @article{Habicht2018, Objectives: Using a longitudinal design, the present study sought to substantiate indications from two previous cross-sectional studies that hearing aid (HA) experience leads to improved speech processing abilities as quantified using eye-gaze measurements. Another aim was to explore potential concomitant changes in event-related potentials (ERPs) to speech stimuli. Design: Groups of elderly novice (novHA) and experienced (expHA) HA users matched in terms of age and working memory capacity participated. The novHA users were acclimatized to bilateral HA fittings for up to 24 weeks. The expHA users continued to use their own HAs during the same period. The participants' speech processing abilities were assessed after 0 weeks (novHA: N = 16; expHA: N = 14), 12 weeks (novHA: N = 16; expHA: N = 14), and 24 weeks (N = 10 each). To that end, an eye-tracking paradigm was used for estimating how quickly the participants could grasp the meaning of sentences presented against background noise together with two similar pictures that either correctly or incorrectly depicted the meaning conveyed by the sentences (the “processing time”). Additionally, ERPs were measured with an active oddball paradigm requiring the participants to categorize word stimuli as living (targets) or nonliving (nontargets) entities. For all measurements, the stimuli were spectrally shaped according to individual real-ear insertion gains and presented via earphones. Results: Concerning the processing times, no changes across time were found for the expHA group. After 0 weeks of HA use, the novHA group had significantly longer (poorer) processing times than the expHA group, consistent with previous findings. After 24 weeks, a significant mean improvement of ~30% was observed for the novHA users, leading to a performance comparable with that of the expHA group. Concerning the ERPs, no changes across time were found. Conclusions: The results from this exploratory study are consistent with the view that auditory acclimatization to HAs positively impacts speech comprehension in noise. Further research is needed to substantiate them. |
Lisena Hasanaj; Sujata P. Thawani; Nikki Webb; Julia D. Drattell; Liliana Serrano; Rachel C. Nolan; Jenelle Raynowska; Todd E. Hudson; John-Ross Rizzo; Weiwei Dai; Bryan McComb; Judith D. Goldberg; Janet C. Rucker; Steven L. Galetta; Laura J. Balcer Rapid number naming and quantitative eye movements may reflect contact sport exposure in a collegiate ice hockey cohort Journal Article In: Journal of Neuro-Ophthalmology, vol. 38, no. 1, pp. 24–29, 2018. @article{Hasanaj2018, Objective: We determined the relation of rapid number naming time scores on the King-Devick (K-D) test to video-oculographic eye movement performance during pre-season baseline assessments in a collegiate ice hockey team cohort. Background: The K-D test is a reliable visual performance measure that is a sensitive sideline indicator of concussion when time scores worsen (lengthen) from pre-season baseline. Methods: Athletes from collegiate ice hockey team received pre-season baseline testing as part of an ongoing study of rapid sideline/ rinkside performance measures for concussion. These included the K-D test (spiral bound cards and tablet computer versions). Participants also performed a laboratory-based version of the K-D test with simultaneous infrared-based video-oculographic recordings using EyeLink 1000+. This allowed measurement of temporal and spatial characteristics of eye movements, including saccade velocity, duration and inter-saccadic intervals. Results: Among 13 male athletes, aged 18 to 23 years (mean 20.5+/-1.6 years), prolongation of the inter-saccadic interval (ISI, a combined measure of saccade latency and fixation duration) was the eye movement measure most associated with slower baseline KD scores (mean 38.2+/-6.2 seconds |
Samson Chota; Canhuang Luo; Sébastien M. Crouzet; Léa Boyer; Ricardo Kienitz; Michael C. Schmid; Rufin VanRullen Rhythmic fluctuations of saccadic reaction time arising from visual competition Journal Article In: Scientific Reports, vol. 8, pp. 15889, 2018. @article{Chota2018, Recent research indicates that attentional stimulus selection could be a rhythmic process. In monkey, neurons in V4 and IT exhibit rhythmic spiking activity in the theta range in response to a stimulus. When two stimuli are presented together, the rhythmic neuronal responses to each occur in anti-phase, a result indicative of competitive interactions. In addition, it was recently demonstrated that these alternating oscillations in monkey V4 modulate the speed of saccadic responses to a target flashed on one of the two competing stimuli. Here, we replicate a similar behavioral task in humans (7 participants, each performed 4000 trials) and report a pattern of results consistent with the monkey findings: saccadic response times fluctuate in the theta range (6 Hz), with opposite phase for targets flashed on distinct competing stimuli. |
Jan Churan; Doris I. Braun; Karl R. Gegenfurtner; Frank Bremmer Comparison of the precision of smooth pursuit in humans and head unrestrained monkeys Journal Article In: Journal of Eye Movement Research, vol. 11, no. 4, pp. 1–15, 2018. @article{Churan2018, Direct comparison of results of humans and monkeys is often complicated by differences in experimental conditions. We replicated in head unrestrained macaques experiments of a recent study comparing human directional precision during smooth pursuit eye movements (SPEM) and saccades to moving targets (Braun & Gegenfurtner, 2016). Directional precision of human SPEM follows an exponential decay function reaching optimal values of 1.5°-3° within 300 ms after target motion onset, whereas precision of initial saccades to moving targets is slightly better. As in humans, we found general agreement in the development of directional precision of SPEM over time and in the differences between directional precision of initial saccades and SPEM initiation. However, monkeys showed overall lower precision in SPEM compared to humans. This was most likely due to differences in experimental conditions, such as in the stabilization of the head, which was by a chin and a head rest in human subjects and unrestrained in monkeys. |
Thérèse Collins; Pierre O. Jacquet TMS over posterior parietal cortex disrupts trans-saccadic visual stability Journal Article In: Brain Stimulation, vol. 11, no. 2, pp. 390–399, 2018. @article{Collins2018, Background: Saccadic eye movements change the retinal location of visual objects, but we do not experience the visual world as constantly moving, we perceive it as seamless and stable. This visual stability may be achieved by an internal or efference copy of each saccade that, combined with the retinal information, allows the visual system to cancel out or ignore the self-caused retinal motion. Objective: The current study investigated the underlying brain mechanisms responsible for visual stability in humans with online transcranial magnetic stimulation (TMS). Methods: We used two classic tasks that measure efference copy: the double-step task and the in-flight displacement task. The double-step task requires subjects to make two memory-guided saccades, the second of which depends on an accurate internal copy of the first. The in-flight displacement task requires subjects to report the relative location of a (possibly displaced) target across a saccade. In separate experimental sessions, subjects participated in each task while we delivered online 3-pulse TMS over frontal eye fields (FEF), posterior parietal cortex, or vertex. TMS was contingent on saccade execution. Results: Second saccades were not disrupted in the double-step task, but surprisingly, TMS over FEF modified the metrics of the ongoing saccade. Spatiotopic performance in the in-flight displacement task was altered following TMS over parietal cortex, but not FEF or vertex. Conclusion: These results suggest that TMS disrupted eye-centered position coding in the parietal cortex. Trans-saccadic correspondence, and visual stability, may therefore causally depend on parietal maps. |
Antoine Coutrot; Janet H. Hsiao; Antoni B. Chan Scanpath modeling and classification with hidden Markov models Journal Article In: Behavior Research Methods, vol. 50, pp. 362–379, 2018. @article{Coutrot2018, How people look at visual information reveals fundamental information about them; their interests and their states of mind. Previous studies showed that scanpath, i.e., the sequence of eye movements made by an observer exploring a visual stimulus, can be used to infer observer- related (e.g., task at hand) and stimuli-related (e.g., image semantic category) information. However, eye movements are complex signals and many of these studies rely on lim- ited gaze descriptors and bespoke datasets. Here, we provide a turnkey method for scanpath modeling and classification. This method relies on variational hidden Markov models (HMMs) and discriminant analysis (DA). HMMs encap- sulate the dynamic and individualistic dimensions of gaze behavior, allowing DA to capture systematic patterns diag- nostic of a given class of observers and/or stimuli. We test our approach on two very different datasets. Firstly, we use fixations recorded while viewing 800 static natural scene images, and infer an observer-related characteristic: the task at hand. We achieve an average of 55.9% correct classification rate (chance = 33%). We show that correct classification rates positively correlate with the number of salient regions present in the stimuli. Secondly, we use eye positions recorded while viewing 15 conversational videos, and infer a stimulus-related characteristic: the presence or absence of original soundtrack. We achieve an average 81.2% correct classification rate (chance = 50%). HMMs allow to integrate bottom-up, top-down, and oculomotor influences into a single model of gaze behavior. This syn- ergistic approach between behavior and machine learning will open new avenues for simple quantification of gazing behavior. We release SMAC with HMM, a Matlab toolbox freely available to the community under an open-source license agreement. |
Deborah A. Cronin; David E. Irwin Visual working memory supports perceptual stability across saccadic eye movements Journal Article In: Journal of Experimental Psychology: Human Perception and Performance, vol. 44, no. 11, pp. 1739–1759, 2018. @article{Cronin2018, Vision is suppressed during saccadic eye movements. To create a stable perception of the visual world we must compensate for the gaps in visual input caused by this suppression. Some theories of perceptual stability, such as the Saccade Target Object Theory (McConkie & Currie, 1996), propose that stability relies on object correspondence across saccades. According to these views, the visual system encodes features of the saccade target into visual working memory (VWM) before a saccade is made. After the saccade, participants attempt to locate those features within a small region near the fovea. If this locating process succeeds, perceptual stability is maintained. The present study investigated directly whether perceptual stability relies on VWM. If it does, perceived stability should be impaired when VWM is loaded with other visual information. Participants detected saccade target displacements while simultaneously maintaining a VWM or verbal working memory (AWM) load. In three experiments, a VWM load negatively impacted participants' ability to detect saccade target displacements and the saccade target displacement task negatively impacted memory for VWM task items. Neither of these effects were apparent when AWM was loaded, suggesting that performance on VWM and saccade target displacement detection tasks, and thus perceptual stability, relies on VWM resources. |
Jean-Bernard Damasse; Laurent U. Perrinet; Laurent Madelain; Anna Montagnini Reinforcement effects in anticipatory smooth eye movements Journal Article In: Journal of Vision, vol. 18, no. 11, pp. 1–18, 2018. @article{Damasse2018, When predictive information about target motion is available, anticipatory smooth pursuit eye movements (aSPEM) are consistently generated before target appearance, thereby reducing the typical sensorimotor delay between target motion onset and foveation.By manipulating the probability for target motion direction, we were able to bias the direction and mean velocity of aSPEM. This suggests that motion-direction expectancy has a strong effect on the initiation of anticipatory movements. To further understand the nature of anticipatory smooth eye movements, we investigated different effects of reinforcement on aSPEM. In a first experiment, the reinforcement was contingent to a particular anticipatory behavior. A monetary reward was associated to a criterion-matching anticipatory velocity as estimated online during the gap before target motion onset. Our results showed a small but significant effect of behavior-contingent monetary reward on aSPEM. In a second experiment, the proportion of rewarded trials was manipulated across motion directions (right vs. left) independently from participants' behavior. Our results indicate that a bias in expected reward does not systematically affect anticipatory eye movements. Overall, these findings strengthen the notion that anticipatory eye movements can be considered as an operant behavior (similar to visually guided ones), whereas the expectancy for a noncontingent reward cannot efficiently bias them. |
Frederic R. Danion; J. Randall Flanagan Different gaze strategies during eye versus hand tracking of a moving target Journal Article In: Scientific Reports, vol. 8, pp. 10059, 2018. @article{Danion2018, The ability to visually track, using smooth pursuit eye movements, moving objects is critical in both perceptual and action tasks. Here, by asking participants to view a moving target or track it with their hand, we tested whether different task demands give rise to different gaze strategies. We hypothesized that during hand tracking, in comparison to eye tracking, the frequency of catch-up saccades would be lower, and the smooth pursuit gain would be greater, because it limits the loss of stable retinal and extra-retinal information due to saccades. In our study participants viewed a visual target that followed a smooth but unpredictable trajectory in a horizontal plane and were instructed to either track the target with their gaze or with a cursor controlled by a manipulandum. Although the mean distance between gaze and target was comparable in both tasks, we found, consistent with our hypothesis, an increase in smooth pursuit gain and a decrease in the frequency of catch-up saccades during hand tracking. We suggest that this difference in gaze behavior arises from different tasks demands. Whereas keeping gaze close to the target is important in both tasks, obtaining stable retinal and extra-retinal information is critical for guiding hand movement. |
Suryadeep Dash; Tyler R. Peel; Stephen G. Lomber; Brian D. Corneil In: eNeuro, vol. 5, no. 2, pp. 1–16, 2018. @article{Dash2018, A neural correlate for saccadic reaction times (SRTs) in the gap saccade task is the level of low-frequency activity in the intermediate layers of the superior colliculus (iSC) just before visual target onset: greater levels of such preparatory iSC low-frequency activity precede shorter SRTs. The frontal eye fields (FEFs) are one likely source of iSC preparatory activity, since FEF preparatory activity is also inversely related to SRT. To better understand the FEF's role in saccade preparation, and the way in which such preparation relates to SRT, in two male rhesus monkeys, we compared iSC preparatory activity across unilateral reversible cryogenic inactivation of the FEF. FEF inactivation increased contralesional SRTs, and lowered ipsilesional iSC preparatory activity. FEF inactivation also reduced rostral iSC activity during the gap period. Importantly, the distributions of SRTs generated with or without FEF inactivation overlapped, enabling us to conduct a novel population-level analyses examining iSC preparatory activity just before generation of SRT-matched saccades. When matched for SRTs, we observed no change during FEF inactivation in the relationship between iSC preparatory activity and SRT-matched saccades across a range of SRTs, even for the occasional express saccade. Thus, while our results emphasize that the FEF has an overall excitatory influence on preparatory activity in the iSC, the communication between the iSC and downstream oculomotor brainstem is unaltered for SRT-matched saccades. |
Jelmer P. De Vries; Stefan Van der Stigchel; Ignace T. C. Hooge; Frans A. J. Verstraten The lifetime of salience extends beyond the initial saccade Journal Article In: Perception, vol. 47, no. 2, pp. 125–142, 2018. @article{DeVries2018, Several models of selection in search predict that saccades are biased toward conspicuous objects (also referred to as salient objects). Indeed, it has been demonstrated that initial saccades are biased toward the most conspicuous candidate. However, in a recent study, no such bias was found for the second saccade, and it was concluded that the attraction of conspicuous elements is limited to only short-latency initial saccades. This conclusion is based on only a single feature manipulation (orientation contrast) and conflicts with the prediction of influential salience models. Here, we investigate whether this result can be generalized beyond the domain of orientation. In displays containing three luminance annuli (Experiment 1), we find a considerable bias toward the most conspicuous candidate for the second saccade. In Experiment 1, the target could not be discriminated peripherally. When we made the target peripherally discriminable, the second saccade was no longer biased toward the more conspicuous candidate (Experiment 2). Thus, conspicuity plays a role in saccadic selection beyond the initial saccade. Whether second saccades are biased toward conspicuous objects appears to depend on the type of feature contrast underlying the conspicuity and the peripheral discriminability of target properties. |
Isabel Dombrowe Saccadic inhibition in a guided saccade task Journal Article In: PeerJ, vol. 2018, no. 6, pp. 1–18, 2018. @article{Dombrowe2018, The eye movement system reacts very systematically to visual transients that are presented during the planning phase of a saccade. About 50 to 70 ms after the onset of a transient, the number of saccades that are started decreases, a phenomenon that has been termed saccadic inhibition. Saccades started just before this time window are hypometric compared to regular saccades, presumably because the presentation of the transient stops them in mid-flight. Recent research investigating the properties of repeated saccades to fixed locations found that these early saccades were additionally faster than expected from the main sequence relation, suggesting that a saccadic dead time during which saccades can no longer be modified does not exist. The present study investigated the properties of saccades to random locations in a guided saccade task. As expected, early saccades starting just before the saccadic inhibition dip in frequency were hypometric. Their velocity profiles implied that these saccades were actively stopped after reaching peak velocity. However, the peak velocities of these saccades did not generally deviate from the main sequence relation. The question whether an active stop of early saccades is incompatible with the idea of a saccadic dead time is open to debate. |
Zhenlan Jin; Shulin Yue; Junjun Zhang; Ling Li Task-irrelevant emotional faces impair response adjustments in a double-step saccade task Journal Article In: Cognition and Emotion, vol. 32, no. 6, pp. 1347–1354, 2018. @article{Jin2018, Cognitive control enables us to adjust behaviours according to task demands, and emotion influences the cognitive control. We examined how task-irrelevant emotional stimuli impact the ability to inhibit a prepared response and then programme another appropriate response. In the study, either a single target or two sequential targets appeared after emotional face images (positive, neutral, and negative). Subjects were required to freely viewed the emotional faces and make a saccade quickly upon target onset, but inhibit their initial saccades and redirect gaze to the second target if it appeared. We found that subjects were less successful at inhibiting their initial saccades as the inter-target delay increased. Emotional faces further reduced their inhibition ability with a longer delay, but not with a shorter delay. When subjects failed to inhibit the initial saccade, the longer delay produced longer intersaccadic interval. Especially, positive faces lengthened the intersaccadic interval with a longer delay. These results showed mere presence of emotional stimuli influences gaze redirection by impairing the ability to cancel a prepared saccade and delaying the programming of a corrective saccade. Therefore, we propose that the modulation of response adjustment exerted by emotional faces is related to the stage of initial response programming. |
Yan-Ying Ju; Yen-Hsiu Liu; Chih-Hsiu Cheng; Yu-Lung Lee; Shih-Tsung Chang; Chi-Chin Sun; Hsin-Yi Kathy Cheng Effects of combat training on visuomotor performance in children aged 9 to 12 years - an eye-tracking study Journal Article In: BMC Pediatrics, vol. 18, no. 1, pp. 1–9, 2018. @article{Ju2018, Background: Data on visuomotor performance in combat training and the effects of combat training on visuomotor performance are limited. This study aimed to investigate the effects of a specially designed combat sports (CS) training program on the visuomotor performance levels of children. Methods: A pre–post comparative design was implemented. A total of 26 students aged 9–12 years underwent 40-min CS training sessions twice a week for 8 weeks during their physical education classes. The CS training program was designed by a karate coach and a motor control specialist. The other 30 students continued their regular activities and were considered as a control group. Each student's eye movement was monitored using an eye tracker, whereas the motor performance was measured using a target hitting system with a program-controlled microprocessor. The measurements were taken 8 weeks before (baseline), 1 day before (pretest), and 1 week after (posttest) the designated training program. The task used for evaluating these students was hitting or tracking random illuminated targets as rapidly as possible. A two-way analysis of variance [group(2) × time(3)] with repeated measures of time was performed for statistical analysis. Results: For the children who received combat training, although the eye response improvement was not significant, both the primary and secondary saccade onset latencies were significantly earlier compared to the children without combat training. Both groups of students exhibited improvement in their hit response times during the target hitting tasks. Conclusion: The current finding supported the notion that sports training efforts essentially enhance visuomotor function in children aged 9–12 years, and combat training facilitates an earlier secondary saccade onset. |
Devin H. Kehoe; Maryam Rahimi; Mazyar Fallah Perceptual color space representations in the oculomotor system are modulated by surround suppression and biased selection Journal Article In: Frontiers in Systems Neuroscience, vol. 12, pp. 1, 2018. @article{Kehoe2018, The oculomotor system utilizes color extensively for planning saccades. Therefore, we examined how the oculomotor system actually encodes color and several factors that modulate these representations: attention-based surround suppression and inherent biases in selecting and encoding color categories. We measured saccade trajectories while human participants performed a memory-guided saccade task with color targets and distractors and examined whether oculomotor target selection processing was functionally related to the CIE (x,y) color space distances between color stimuli and whether there were hierarchical differences between color categories in the strength and speed of encoding potential saccade goals. We observed that saccade planning was modulated by the CIE (x,y) distances between stimuli thus demonstrating that color is encoded in perceptual color space by the oculomotor system. Furthermore, these representations were modulated by (1) cueing attention to a particular color thereby eliciting surround suppression in oculomotor color space and (2) inherent selection and encoding biases based on color category independent of cueing and perceptual discriminability. Since surround suppression emerges from recurrent feedback attenuation of sensory projections, observing oculomotor surround suppression suggested that oculomotor encoding of behavioral relevance results from integrating sensory and cognitive signals that are pre-attenuated based on task demands and that the oculomotor system therefore does not functionally contribute to this process. Second, although perceptual discriminability did partially account for oculomotor processing differences between color categories, we also observed preferential processing of the red color category across various behavioral metrics. This is consistent with numerous previous studies and could not be simply explained by perceptual discriminability. Since we utilized a memory-guided saccade task, this indicates that the biased processing of the red color category does not rely on sustained sensory input and must therefore involve neural areas associated with the highest levels of visual processing involved in visual working memory. |
Derek Kellar; Sharlene Newman; Franco Pestilli; Hu Cheng; Nicholas L. Port Comparing fMRI activation during smooth pursuit eye movements among contact sport athletes, non-contact sport athletes, and non-athletes Journal Article In: NeuroImage: Clinical, vol. 18, pp. 413–424, 2018. @article{Kellar2018, Objectives: Though sub-concussive impacts are common during contact sports, there is little consensus whether repeat blows affect brain function. Using a “lifetime exposure” rather than acute exposure approach, we examined oculomotor performance and brain activation among collegiate football players and two control groups. Our analysis examined whether there are group differences in eye movement behavioral performance and in brain activation during smooth pursuit. Methods: Data from 21 off-season Division I football “starters” were compared with a) 19 collegiate cross-country runners, and b) 11 non-athlete college students who were SES matched to the football player group (total N = 51). Visual smooth pursuit was performed while undergoing fMRI imaging via a 3 Tesla scanner. Smooth pursuit eye movements to three stimulus difficulty levels were measured with regard to RMS error, gain, and lag. Results: No meaningful differences were found for any of the standard analyses used to assess smooth pursuit eye movements. For fMRI, greater activation was seen in the oculomotor region of the cerebellar vermis and areas of the FEF for football players as compared to either control group, who did not differ on any measure. Conclusion: Greater cerebellar activity among football players while performing an oculomotor task could indicate that they are working harder to compensate for some subtle, long-term subconcussive deficits. Alternatively, top athletes in a sport requiring high visual motor skill could have more of their cerebellum and FEF devoted to oculomotor task performance regardless of subconcussive history. Overall, these results provide little firm support for an effect of accumulated subconcussion exposure on brain function. |
Krzysztof Krejtz; Andrew T. Duchowski; Anna Niedzielska; Cezary Biele; Izabela Krejtz Eye tracking cognitive load using pupil diameter and microsaccades with fixed gaze Journal Article In: PLoS ONE, vol. 13, no. 9, pp. e0203629, 2018. @article{Krejtz2018, Pupil diameter and microsaccades are captured by an eye tracker and compared for their suitability as indicators of cognitive load (as beset by task difficulty). Specifically, two metrics are tested in response to task difficulty: (1) the change in pupil diameter with respect to inter- or intra-trial baseline, and (2) the rate and magnitude of microsaccades. Participants performed easy and difficult mental arithmetic tasks while fixating a central target. Inter-trial change in pupil diameter and microsaccade magnitude appear to adequately discriminate task difficulty, and hence cognitive load, if the implied causality can be assumed. This paper's contribution corroborates previous work concerning microsaccade magnitude and extends this work by directly comparing microsaccade metrics to pupillometric measures. To our knowledge this is the first study to compare the reliability and sensitivity of task-evoked pupillary and microsaccadic measures of cognitive load. |