Recording and analysis of eye movements
Oculometer adapted for MRI environments :
The technical facility includes an MRI-compatible monocular oculometer (ASL model E6000 - Immersion ) with the optics offset by a mirror system. It has an accuracy of 0.5° and a resolution of 0.25°. The sampling rate is 60 / 120 / 240 Hz. The distance of use is 3.50 m max. Long focal length optics send the image of the eye to a 25-cm-diameter antenna. The system has the « Eyepos » software for research, calibration, and image display and recording operations ; Eyenal data analysis software ; Fixplot software for superimposing eye direction trajectories ; and SDK (software development kit), which integrates head movement and eye path data into other applications like C++, Matlab, and Presentation
Oculometers not suitable for MRI :
- CHRONOS (Space room) :
Chronos system based on the digital recording of binocular images with a video camera, and their storage (CMOS technology). Oculometer with monocular and binocular configuration available in the "space room", not MRI compatible. Cameras on headsets and dichroic mirrors, with IR LEDs (940 nm). Sampling rate is 50, 100 or 200 Hz. Analysis is done off-line using the recorded files. It combines horizontal, vertical and twisting movements. Accuracy 0.2° and resolution of the order of 0.05°.
Based on video image processing technology (IR camera and illumination). Sampling rate 240/350 Hz (up to 2005 version) and 500/1250 Hz (2006 version). Head held at chin and forehead. Pupil tracking technique. This monocular oculometer equipped with an infrared camera works in real time and can record data extremely precisely, in both space and time. Numerous adjustable settings (contrast, brightness, pupil diameter, etc) enable the pupil to be located quickly and in a very stable way.
In CerCo, this oculometer is interfaced with the Matlab PsychToolBox extension, which allows the eye movement recordings to be checked in real time and visual stimuli to be presented rapidly in a controlled manner.
IR-illuminated video recording system. Exists in human and non-human primate versions (monocular or binocular). Resolution 0.06°, sampling rate up to 240 Hz.
The Iview software Iview also provides post-hoc processing of eye movements by decomposing the eye position signal into events (saccades, fixations, blinks) with precise analysis of the saccade latency and the image point targeted by the saccade
Mise à jour 14/02/2011