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 subjects will generate a high number of incorrect prosaccades in an antisaccade task if the fixation point is extinguished 200 ms before the stimulus appears and if a valid cue for the subsequent antisaccade is given 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 to investigate the neural processes associated with correct antisaccades and incorrect prosaccades in this task. Correct antisaccades and incorrect prosaccades were associated with a negative potential with a maximal amplitude around stimulus onset over the dorsomedial frontal cortex. This potential was higher prior to correct antisaccades than prior to incorrect prosaccades. The execution of a correct antisaccade was preceded by a shift of a negative potential from the parietal hemisphere contralateral to the visual stimulus towards the parietal hemisphere ipsilateral to the stimulus. These results support the view that the 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 stimulus in the hemifield ipsilateral to the stimulus before generating a motor response.