Compensation of Parietal Cortex for perturbations to Frontal Cortex

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Frontal Eye Field (FEF) and Parietal Eye Field (PEF) have both been involved in the control of saccades but the role of these regions for vector inversion is still not clear. Recent evidence suggested that after FEF disruption, PEF compensates by showing increased BOLD activity. Equally important, Dorsolateral Prefrontal Cortex (DLPFC) and FEF were found to be important for executive control of saccades. In the antisaccade task participants have to suppress an automatic saccade towards a visual target and generate instead a voluntary saccade towards the opposite direction. This task allows us to dissociate between the brain regions that are critically involved in executive control but also in vector inversion process. To that end, we first used cTBS to right frontal eye fields (rFEF), right dorsolateral prefrontal cortex (rDLPFC) or a control site and we subsequently applied single-pulse TMS to right parietal eye fields (rPEF) at different times. Hereafter, participants performed the pro-/anti-saccade task and the amplitude, reaction time and error rates were assessed. rFEF cTBS relative to rS1 cTBS induced hypometric contralateral antisaccades (i.e., when the visual target was on the right side) and by applying single-pulses over rPEF between 120 ms and 210 ms, the deficits became more pronounced. After cTBS to rDLPFC, as compared to rS1 cTBS, we observed reduced reaction time for ipsilateral prosaccades. These results confirm that FEF and PEF are critically involved in motor saccade planning and DLPFC is important for executive control of saccades.
Faculteit der Sociale Wetenschappen