Somatotopic organization of spider monkey somatic sensory cerebral cortex

Organization of the tactile receiving area of the postcentral gyrus of the spider‐monkey (Ateles) has been investigated using microelectrode recording procedures. The neocortical region in which single units or unit clusters respond to light mechanical region in skin (SmI) is smaller than the tactile receiving area as defined by earlier evoked potentials studies, failing to extend into sylvian sulcus or to the posterior margin of the postcentral gyrus. It forms a precise, detailed, and somatotopically organized pattern of representation of the complete contralateral body surface. The sensory sequence is orderly and continuous from tail to tongue with one exception, each body region in represented by a band of cortical tissue extending anteroposteriorly across SmI. The ratio, area of glabrous surface of the hand as it is for the glabrous tail pad, which correlates with the greater tactile acuity of the former.