Influence of the Cerebral Cortex on the Cuneate Nucleus of the Monkey

Abstract

NEARLY all neurones in the dorsal column nuclei of the cat are either excited or inhibited by stimulation of the pericruciate cortex^1–3, the excitation being carried entirely by the pyramidal tract, while inhibition involves an additional route^2,3. The cortically excited neurones occupy deep and rostral sites in the dorsal column nuclei, near the pyramidal terminations^4,5, while the cortically inhibited neurones are found more superficially. The latter, usually hair-sensitive neurones, possess peripheral inhibitory surrounds⁶; they may be identified with the cluster neurones, receiving large synaptic terminals⁷. The former are more often touch-sensitive or pressure-sensitive neurones possessing peripheral facilitatory surrounds⁶. Thus, neurones excited from one region of cortex are similarly excited from other cortical regions, ipsilateral and contralateral; the same rule holds for inhibition^1,2. Few neurones have been observed with both types of cortical influence or with no cortical influence whatever.