THE EFFECT OF SATIETY ON RESPONSES OF GUSTATORY NEURONS IN THE AMYGDALA OF ALERT CYNOMOLGUS MACAQUES

An alert cynomolgus macaque was fed a sweet solution to satiety as the activity of a gustatory neuron in the amygdala was recorded to that s olution and to four other taste stimuli. This experiment was conducted a total of 14 times in two monkeys. The responses of individual neuro ns to the satiety stimuli were suppressed by as Little as 1%, and as m uch as 100% by the induction of satiety (mean suppression = 58%). Nine of the 14 cells responded to the satiety solution with excitation, an d their responses were suppressed by a mean of 62% by satiety. Five ne urons responded with inhibition, and their responses were suppressed b y a mean of 50%. Responses to other taste stimuli, not associated with satiety, were affected to a lesser extent. The amygdala is a taste re lay between the primary gustatory cortex, where satiety has no influen ce on responses to taste stimuli, and the lateral hypothalamic area wh ere the effect of satiety is total. The data presented here indicate t hat the amygdala is a functional as well as anatomical intermediary be tween these two areas, and serves as a stage in the process through wh ich sensory stimuli are imbued with motivational significance.