Set related and premovement related activity of primate primary somatosensory cortical neurons depends upon stimulus modality and subsequent movement.

The activity of primate primary somatosensory (SI) cortical neurons was examined in monkeys trained to perform wrist movements in response to visual or vibratory cues using single-unit, extracellular recording techniques. Neuronal discharge rates associated with peripheral stimulus onset often differed depending upon the modality of the stimulus and whether the animals were instructed to make wrist movements or withhold them. Premovement activity changes that led muscle activation commonly were of different magnitude depending on the modality of the triggering stimulus. This was true both for neurons that responded to vibratory stimuli and those that exhibited no vibratory response. These observations suggest that the activity of SI neurons may be influenced by central modulatory as well as peripheral inputs during task behavior.