Supplementary Sensory Area

Abstract

Relatively little attention has been devoted to the medial aspect of the parietal cortex, especially with respect to its neuronal responses to somatic sensory stimuli. However, the stimulation of neurons in three different sites in the medial parietal cortex (in the precuneate lobule) of a human has been reported to evoke tingling sensations in the contralateral leg, arm and face (30). More recently, other investigators have reported that electrical stimulation of the medial posterior parietal cortex in conscious humans evokes tingling, painful or other paresthesias of the contralateral foot and arm (42). Only a few studies of this medial parietal region have been undertaken in monkeys. Both the motor effects of cortical stimulation in rhesus monkeys (15) and an examination of sensory evoked potentials in the squirrel monkey (4) have suggested the existence of a body representation on the medial surface of the hemisphere, posterior to the S I cortex. Penfield and Jasper (30) have termed this region the “supplementary sensory area.” We have investigated the supplementary sensory cortex in rhesus and cynomolgus monkeys using neuroanatomical and single unit recording methods.