12. The Role of the Human Prefrontal Cortex in the Response Suppression of Eye Movements

Abstract

Increased activity in a population of prefrontal cortex neurons has been shown, in previous studies, to precede correct anti‐saccades in primates. In addition, the time courses of two competing processes in these neurons, task selection (which prepares for an eye movement) and saccade suppression (which prepares for the suppression of an eye movement), intersect at a specific time after the presentation of a coloured instruction cue. The purpose of this study is to use eye tracking behaviour to investigate this intersection point and its role in response suppression in regard to the generation of anti‐saccades in humans. Subjects were instructed before a stimulus appears, using a colour cue, to either look towards the stimulus (pro‐saccade) or away from the stimulus (anti‐saccade). Instruction period times varied from 100ms to 1400ms, in 50ms steps. Based on previous primate electrophysiological data, the ratio of direction errors (pro‐saccades on anti‐saccade trials) to correct anti‐saccades was expected to increase around 400ms to 500ms, when the processes of task selection and saccade suppression diverge. A slight ratio increase was found and full results are forthcoming.