The effect of amygdaloid stimulation on learning in the rat.

In man, the amygdaloid complex or amygdala is a group of closely associated nuclei situated deep in the temporal lobe. Lying partly beneath the uncus, and beside the hippocampus, it becomes blended with the grey matter on its infero-medial aspect, and with the lentiform nucleus dorsally. The differentiation of the various nuclei within the amygdala has remained essentially unchanged from marsupials to man. The study of more primitive animals, however, shows a phylogenetic division into a primitive centromedial group and a more recent basolateral group (Johnson, 1923; Koikegami, Fuse, Yokoyama, Watanabe, & Watanabe, 1955). The centromedial group is composed of the central and medial nuclei and the nucleus of the lateral olfactory tract. The small-celled medial portion of the basal nucleus is also sometimes included