Inhibition induced by forebrain stimulation in the monkey

¹ Department of Physiology, Yale University School of Medicine, New Haven, Connecticut

Eleven monkeys were equipped with fixed or with movable intracerebral electrodes and some of these animals were stimulated by radio control. Several types of inhibitory effects were observed: 1) Specific inhibition of the approaching, taking up, and consummatory phases of alimentary reaction was induced by stimulation of the rostral caudate nucleus and medial septum. Aggressiveness was also inhibited, while other individual and social responses were not modified. The participation of a caudate-septal system in the regulation of food intake is suggested by these experiments. 2) General inhibition of behavior was evoked by caudate stimulation at the commissural level. 3) Partial inhibition of alimentary reactions was elicited by stimulation of amygdala and thalamus. 4) Autonomic inhibition affecting heart rate and respiration followed excitation of the central caudate with single shocks or with frequencies up to 100 cycles/sec. 5) Inhibition of conditioned avoidance was observed during caudate stimulation. However, the same caudate excitation could be used as a cue if the response was reinforced. In self-stimulation experiments the rostral caudate proved to be neutral.

Key Words: cerebral radio stimulation • inhibition behavior • alimentary, autonomic • conditioning, self-stimulation • caudate nucleus, septum, • amygdala, thalamus

Submitted on March 29, 1963