Neurological correlates of social behavior

Experimental evidence obtained over the past decade in nonhuman primates suggests that there are neural structures necessary for the maintenance of social bonds and affiliative behavior, including the amygdaloid nuclei, which is the critical brain area, and two anatomically closely related cortical structures—the temporal pole and posterior medial orbital cortex.

Abstract

Abstract Experimental evidence obtained over the past decade in nonhuman primates suggests that there are neural structures necessary for the maintenance of social bonds and affiliative behavior. These include the amygdaloid nuclei, which is the critical brain area, and two anatomically closely related cortical structures—the temporal pole and posterior medial orbital cortex. Bilateral ablation of any of the areas results in a syndrome that varies from a quantitative decrease in affiliative behavior in confined colonies to total social isolation in naturally free-ranging groups. Lesions of these areas in adult females are also incompatible with the maintenance of the maternal-infant bond, but operated infants thrive and are well cared for. Species-typical behavior will determine the response of group members to lesioned conspecifics, and may vary from attempts to reintegrate the affected subject to attack and ostracism. The amygdaloid nuclei are hypothesized to be essential to placing an emotional bias on sensory information; thus this brain area is sensitive to, and its function dependent on, the social/environmental context of ongoing behavior. Brain impairment per se, does not necessarily result in ostracism and may be compatible with maintenance of social bondings depending upon the neural structures involved, subject's affective state, communication ability, and species typical behaviors. Observations of brain-impaired humans closely parallel studies in nonhuman primates.