The suppressing effect of chlorpromazine treatment on alimentary-social differentiation in amygdala dogs

Experiments were performed on dogs with bilateral electrolytic damage of dorso-medial amygdala. Before the operation dogs were trained in alimentary-social reward differentiation. It consisted in conditioning of instrumental responses of either right or left foreleg to two different tones respectively. Chlorpromazine was injected intramuscularly in 1.5 mg/kg dose during four consecutive days, beginning at third to fifth week after the operation. Amygdala damage produced significant deterioration of the instrumental performance both reinforced by food and by social-sensory rewards. Chlorpromazine produced further dramatic decrease of performance of both responses. It was concluded that chlorpromazine exerts a suppressing effect on motivated behavior reinforced by positive rewards in amygdala dogs. As the effect of chlorpromazine and medial amygdalar damage are summated it may be suggested that the deficit of medial amygdala neurons impairs similar neurochemical mechanisms, (probably dopaminergic and alpha-adrenergic transmission) as does chlorpromazine.