NirX is a world-leader in providing integrated solutions for fNIRS neuroimaging. Integrating their hardware with EyeLink systems is very straightforward, and tests conducted at NirX headquarters in Berlin confirm that, unlike some other infrared eye trackers, EyeLink systems do not create any interference with the NIRS signal.
Integration is achieved via standard TTL signaling, typically via a parallel port on the Display PC (although the parallel port of the EyeLink Host PC can also be used). The only other component required is a Trigger Cable (supplied by NIRx).
During task performance the stimulus presentation software (e.g. Experiment Builder, E-Prime, Presentation, PsychToolBox etc) sends simultaneous TTLs signals to the NIRx equipment and messages to the EyeLink Host PC, marking key trial events, allowing data to be co-registered at the analysis stage. If your stimulus PC does not have a parallel port, commands can be sent over the ethernet connection to the Host PC, so its parallel port can be used instead.
If you have any questions regarding EyeLink-NirX integration, feel free to contact us. We’re always happy to help.