[Callosal connections of the somatosensory area in the primate: anatomical and electrophysiological studies].

In order to study the callosal connections of the hand sensory field of the second somatosensory area of the monkey, experiments were carried out by combining the method of retrograde neuronal tracing with microelectrode recording. In six monkeys, Macaca Irus, single or multiple (5-8) injections of horseradish peroxidase (HRP) were performed into the cortex of the parietal operculum of one side. Neurones retrogradely labelled with HRP (callosal neurones) were found in the post-central gyrus and in the parietal operculum of the contralateral hemisphere. Microelectrode recording from this hemisphere showed that the cortical zones of both the first and the second somatosensory area containing neurones excited by sensory stimulation of the contralateral hand also contained HRP-positive neurones.