Cortical potentials during gap and non-gap paradigms using manual responses in humans.

An experiment was conducted on naive human subjects to measure the time benefits on finger reaction times produced by the offset of a central fixation point 200 ms before the appearance of a target stimulus in the periphery. Subjects produced a shift advancement of manual reaction times. Simultaneously, the event-related potentials were recorded. The gap paradigm induced offset visual evoked potentials and a frontal negativity, it also induced a higher P300 than the non-gap condition. The results suggest that the gap promotes the speeding of the response by a cortical priming.