Neural correlates to emotional expression and social cognition in the monkey amygdala

Abstract

The amygdala has been implicated in both social cognition to infer emotional states of other individuals (which processes are independent of autonomic activity) and own emotional expression based on biological evaluation (which processes are correlated to autonomic activity). Previously we reported that activity of some amygdalar neurons was correlated to biological significance of the objects. In the present study more than 500 monkey amygdalar neurons were recorded during discrimination of various facial expressions. Some neurons were further tested with approaching of the experimenter or various objects toward the monkey, and with various experimenter's actions. Autonomic activity (pupil radius) of the monkey, which reflected emotional expression, were simultaneously recorded. Results indicated that activity of some neurons increased when the experimenter, the hand of the experimenter, and novel objects approached toward the monkey. Pupil radius also increased during this approaching. These neurons did not respond to the photos of various facial expressions. Activity of other neurons increased when the experimenter moved his arm or leg. We are now analyzing correlation between pupil radius and activity of these neurons to determine whether the neurons were involved in emotional expression/biological evaluation or social cognition. Based on these findings, we will discuss about neural mechanisms of social cognition and biological evaluation in the monkey amygdala. [Jpn J Physiol 54 Suppl:S189 (2004)]