Induced modulations in autonomic efferent neuron activity

¹ Departments of Physiology, State University of New York Downstate Medical Center, New York City, and Kobe Medical College, Kobe, Japan

A study was made of the extent to which autonomic responses follow stimulation of the cerebellar cortex, somatic, and visceral afferent nerves. Activity of units in splanchnic and mesenteric nerves, in postganglionic fibers from the coeliac ganglion, and in vagus nerve branches to the stomach was recorded by microelectrodes. Stimulation of visceral, muscle, and skin afferents evoked discharges in sympathetic fibers and augmented their spontaneous activity. Sympathetic and parasympathetic efferents showed reciprocal action in that, when activity in one was either spontaneously or reflexly increased, activity in the other diminished. Chemical stimulation of the cerebellar cortex by application of sodium glutamate produced an increase in activity of both sympathetic and parasympathetic nerves and an increase in systemic blood pressure. Changes in blood pressure also modified activities of the autonomic efferents. The spontaneous discharges were not much affected by decerebration or decerebellation but section below the medulla at least temporarily abolished tonic activity in the units studied.

Key Words: cerebellar control of autonomic neuron discharges • reciprocal action in autonomic systems • cerebellar excitation by microinjection of sodium glutamate • autonomic and somatic integration • unitary activities • somatic nerve stimulation • sodium glutamate, excitatory action

Submitted on February 25, 1963