The amygdala, synaptic plasticity, and fear memory.

The nature and mechanisms of synaptic plasticity in the amygdala and the relation of amygdaloid plasticity to behavior are exciting new areas of study in neuroscience. These issues were at the heart of presentations by Paul Chapman, Michael Fanselow, Patricia Shinnick-Gallagher, and Michael Rogawski in a session entitled "Long-Term Plasticity in Amygdala Synaptic Transmission" that was held at the conference featured in this volume. In this chapter, I briefly summarize these talks and give my perspective on the presentations as the session chair. I argue that we must first understand the role of the amygdala in learning and memory in order to understand the contribution of amygdaloid synaptic plasticity to behavior. Although it is generally agreed that the amygdala is involved in several forms of emotional learning and memory such as pavlovian fear conditioning, a recent debate has emerged concerning the precise role of the amygdala in learning versus performing fear responses. I discuss data from my laboratory that unravel this issue. I argue that the basolateral complex of the amygdala (BLA) normally plays an essential role in associative processes in fear conditioning. Nonetheless, rats with BLA lesions acquire and express conditional fear under some conditions. A neuroanatomical model that accounts for these data is presented.