EVENT-RELATED POTENTIALS ASSOCIATED WITH CORRECT AND INCORRECT RESPONSES IN A CUED ANTISACCADE TASK

In an antisaccade task, subjects are instructed to inhibit a reflexive saccade towards a peripheral stimulus flash and to generate a saccade in the opposite direction. It has been shown recently that normal sub jects will generate a high number of incorrect prosaccades in an antis accade task if the fixation point is extinguished 200 ms before the st imulus appears and if a valid cue for the subsequent antisaccade is gi ven during this gap period. In the present study we recorded cerebral event-related potentials from 19 scalp electrodes from normal subjects prior to correct and incorrect responses in a cued antisaccade task t o investigate the neural processes associated with correct antisaccade s and incorrect prosaccades in this task. Correct antisaccades and inc orrect prosaccades were associated with a negative potential with a ma ximal amplitude around stimulus onset over the dorsomedial frontal cor tex. This potential was higher prior to correct antisaccades than prio r to incorrect prosaccades. The execution of a correct antisaccade was preceded by a shift of a negative potential from the parietal hemisph ere contralateral to the visual stimulus towards the parietal hemisphe re ipsilateral to the stimulus. These results support the view that th e supplementary eye fields participate in the inhibition of incorrect saccades in a cued antisaccade task and show that the parietal cortex participates in generating a neural representation of the visual stimu lus in the hemifield ipsilateral to the stimulus before generating a m otor response.