CHOLINERGIC SYNAPSES IN VENTROMEDIAL HYPOTHALAMUS FOR SUPPRESSION OF OPERANT BEHAVIOR BY PUNISHMENT AND SATIETY

Cannula-produced lesions or direct application of crystalline atropine methyl nitrate in the ventromedial hypothalamus and nearby structures substantially reduced the suppressant effect of punishment on food-rewarded operant behavior. 41 adult male albino rats were Ss. Hypothalamic application of atropine also increased spontaneous motor activity and reduced the suppressant effect of satiation on food-rewarded operant behavior. In the same Ss, however, atropine failed to disinhibit feeding responses suppressed by satiation. These and other findings suggest that the suppressant effects of satiation or operant behavior and feeding behavior are mediated by different systems. The system that suppresses operant behavior contains cholinergic synapses in the medial hypothalamus. The system that suppresses feeding either forms noncholinergic synapses in the hypothalamus or does not synapse at this level. (24 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.