Getting Started: Getting Started with Brain Products Integration
Connecting up the Equipment

The integration between a Brain Products EEG device and an EyeLink tracker can take different paths, depending on the Brain Products hardware and software you have access to. Please see below for a diagram showing the viable options.
  • Option #1: TTL  to Brain Products EEG Device and simultaneous Message via Ethernet to EyeLink Host PC. This solution should work with all Brain Products devices. You connect the parallel port on the Display PC directly to the Brain Products Amp via the appropriate cable, and connect to the EyeLink Host PC via ethernet, as per usual. Your stimulus presentation script sends simultaneous TTLs/Messages to mark critical trial events such as stimulus onset / participant response. At the analysis stage the TTLs/Messages can be used to synchronize the two data streams.

  • Option #2: TTL through the USB trigger box. This solution is similar to Option #1, except that no parallel port is required on the Display PC. You send TTL through the USB trigger box directly to the Brain Product Amp, and as with Option 1, simultaneously send a corresponding message to the EyeLink tracker. The messages and the TTL triggers can be aligned during data analysis to synchronize the two data streams.

  • Option #3: TTL to EyeLink and Brain Products EEG device.  Key events can be marked in both data streams simultaneously by sending a TTL through a  "Y-shaped" parallel port splitter cable to both the Brain Products EEG Device and EyeLink Host PC.  Alternatively, you can connect the parallel port on the EyeLink Host PC directly to the Brain Products Amp. This setup is particularly useful if there is no parallel port on the Display PC; a TTL signal is relayed by the EyeLink Host to the Amp upon the reception of a command from the Display PC, sent via the ethernet link.

  • Option #4: Trigger through TCP / IP. With relatively newer Brain Products hardware that supports the Remote Control Server (RCS 2.0), which runs on the BrainVision Recording PC, it is possible to have a TCP / IP solution. This setup requires a network switch that connects to the BrainVision Recording PC, the Stimulus PC, and the EyeLink Host PC. This setup will allow commands to be passed from the Stimulus PC to the BrainVision Recording PC and the EyeLink Host. You can send commands to start/stop recording, to send annotations, to check recording status, etc. via the TCP/IP connection between the Stimulus PC and the BrainVision Recording PC.  Note, annotations sent via TCP / IP are not a substitute for the millisecond precise timing of the TTL event marking methods mentioned above, which are necessary for ERP analysis.  However, the annotation command can provide an additional way to tag your data with arbitrary text codes when timing is not critical, e.g., to define larger blocks of an experiment.


Integration via Experiment Builder

Detailed instructions for Experiment Builder users can be found in the .pdf document which accompanies the Brain Products Example Templates provided in Experiment Builder 2.2 and above. The templates and pdf documents are linked below. Note that, the Experiment Builder template implements the #3 integration solution noted above; nevertheless, you can also use either the BiometricTTL node or the setTTL node in Experiment Builder to implement Option #1 or Option #2 (i.e., TTL through the parallel port or the USB trigger box).

.pdf   BP_EyeLink_Simple_tutorial_version_2.2.0.507.pdf (Size: 2.25 MB / Downloads: 102)

.pdf   BP_Non_EyeLink_Stroop_tutorial_version_2.2.0.507.pdf (Size: 1.85 MB / Downloads: 35)

Integration via other Stimulus Presentation Software

People using E-Prime and the NetStation Extension should consult PST / the relevant manuals for guidance.

For MATLAB+Psychtoolbox, NBS Presentation, PsychoPy, OpenSesame, and other stimulus presentation software, synchronization can be done via TTL signaling. An introduction to TTL signaling outlines the basics of TTL signaling. 

Users should mark critical trial events by simultaneously sending a TTL to the EEG equipment (typically via the parallel port of the Display PC) and writing a message to the EyeLink data. Alternatively, if you have a Desktop Host PC with a parallel port, a DB25 Splitter cable can be used to send the TTL to both the EEG equipment and the Host PC.

Offline synchronization in EEGLab and Fieldtrip

For offline synchronization in software such as EEG-LAB and Fieldtrip, it can be useful to ensure that the message sent to the EyeLink ends with the same 0-255 value that was sent as the TTL.