Neural activation associated with corrective saccades during tasks with fixation, pursuit and saccades.

Corrective saccades are small eye movements that redirect gaze whenever the actual eye position differs from the desired eye position. In contrast to various forms of saccades including pro-saccades, recentering-saccades or memory guided saccades, corrective saccades have been widely neglected so far. The fMRI correlates of corrective saccades were studied that spontaneously occurred during fixation, pursuit or saccadic tasks. Eyetracking was performed during the fMRI data acquisition with a fiber-optic device. Using a combined block and event-related design, we isolated the cortical activations associated with visually guided fixation, pursuit or saccadic tasks and compared these to the activation associated with the occurrence of corrective saccades. Neuronal activations in anterior inferior cingulate, bilateral middle and inferior frontal gyri, bilateral insula and cerebellum are most likely specifically associated with corrective saccades. Additionally, overlapping activations with the established pro-saccade and, to a lesser extent, pursuit network were present. The presented results imply that corrective saccades represent a potential systematic confound in eye-movement studies, in particular because the frequency of spontaneously occurring corrective saccades significantly differed between fixation, pursuit and pro-saccades.