EFFECT OF STIMULATION OF VISUAL CORTEX ON ACTIVITY OF SOMATOSENSORY CORTICAL NEURONS

Abstract

Interaction between responses elicited in the somatosensory cerebral, cortex, following single shock stimulation of the visual cerebral area and the superficial radial nerve or the contralateral somatosensory area, was studied in cats anesthetized with chloralose and immobilized with Faxedil. The range of discharge latencies for the initial spikes from stimulation of the primary visual cortex varied from 8 to 30 msec in the somatosensory cortex. Spike discharges, recorded from a single cortical neuron, were studied using a conditioning-test procedure and were blocked by a preceding response in some neurons; in other neurons, temporal summation was shown. The depressive effect following the first stimulus was found often to last more than 100 msec. Blocking of spike discharges following stimulation of the visual cortex was produced by the hyperpolarized afterpotential in the response elicited from stimulation of the sensory nerve. These results suggest that associative volleys from another cortical area modify activity of the somatosensory cortical neuron as depression or temporal summation.