The amygdala is a prominent limbic structure that plays a key role in emotional coding of environmental stimuli and provides contextual information used for adjusting motivational level that is based on immediate goals. The basolateral nuclear group processes higher-order sensory inputs in all modalities except olfactory, and responds to highly palatable foods, and “multimodal” cues. This is the primary source of amygdaloid input to the VS outside the shell.61,66 The lateral nucleus has a relatively minor input to the VS, while the basal and accessory basal nuclei prominently innervate both the shell and VS striatum outside the shell. The shell is set apart from the rest of the VS by a specific set of connections from the central nucleus, periamygdaloid cortex, and the medial nucleus of the amygdala. The amygdala has few inputs to the DS in primates. In contrast to the amygdala, the hippocampal formation (specifically the subiculum) projects to a more limited region of the VS and is primarily confined to the shell region. Some afferent fibers are also derived from the parasubiculum and part of CA1.103
