Visually induced activity in human frontal motor areas during simple visuomotor performance

Visuomotor tasks elicit neuronal activity in primate motor areas at relativ ely short latencies. Although this early activity embodies features of visu al responses (short latency. stimulus-dependency). its sensory nature has b een questioned. We investigated neural correlates of visuomotor performance in human motor areas using scalp and intracranial event-related potential measures. A simple visuomanual reaction-time task evoked early potentials a t 133-145 ms post-stimulus which occurred much earlier than the motor poten tials of the same region. The amplitude of the early potentials covaried wi th stimulus location and was independent of parameters of the motor respons e. Because of their timing, stimulus-dependency and characteristics of our behavioral task, the early potentials are suggested to reflect neuronal res ponses of sensory nature rather than processing related to pure motor aspec ts of the task. NeuroReport 11:2843-2848 (C) 2000 Lippincott Williams & Wil kins.