Eyetracker-based gaze correction for robust mapping of population receptive fields

- Unstable fixation during retinotopic mapping can be corrected using eyetracker data.
- PRF parameters significantly profit from eyetracker-based correction.
- Reliability of retinotopic mapping results is also improved significantly.
- This method could be especially useful for patients and children.

Functional MRI enables the acquisition of a retinotopic map that relates regions of the visual field to neural populations in the visual cortex. During such a “population receptive field” (PRF) experiment, stable gaze fixation is of utmost importance in order to correctly link the presented stimulus patterns to stimulated retinal regions and the resulting Blood Oxygen Level Dependent (BOLD) response of the appropriate region within the visual cortex. A method is described that compensates for unstable gaze fixation by recording gaze position via an eyetracker and subsequently modifies the input stimulus underlying the PRF analysis according to the eyetracking measures. Here we show that PRF maps greatly improve when the method is applied to data acquired with either saccadic or smooth eye movements. We conclude that the technique presented herein is useful for studies involving subjects with unstable gaze fixation, particularly elderly patient populations.