Cellular Processes and Synaptic Interactions in Nuclei of the Amygdala

The amygdala is a core structure of the limbic system in the brain. Anatomically, the amygdaloid complex comprises ~13 nuclei in the mid-temporal lobe. The amygdaloid complex is important for regulating emotional behavior, anxiety, fear, learning and memory. It is involved in several neurological disorders such as post-traumatic stress syndrome, depression, and temporal lobe epilepsy. The lateral nucleus of the amygdala is the main sensory input station of the amygdala and receives sensory information from cortical and subcortical (thalamic) fields. Thalamic afferents project to the lateral amygdala medially from the internal capsule, whereas cortical afferents arrive from the internal capsule. These two input pathways converge on populations of principal neurons and interneurons, both of which can be identified by characteristic electrophysiological, neurochemical, and morphological properties. Pressing issues for our understanding of the organization and operation of the amygdala are the functional significance of modulatory inputs from various signaling systems and the plasticity of its synaptic circuitry in relation to its pathway-specific inputs. This chapter reviews progress in this regard as far as cellular processes and synaptic interactions in nuclei of the amygdala are concerned which will help with our understanding of neural mechanisms underlying fear, anxiety, and related clinical disorders.