FEAR CONDITIONING INDUCES ASSOCIATIVE LONG-TERM POTENTIATION IN THE AMYGDALA

Long-term potentiation (LTP) is an experience-dependent form of neural plasticity believed to involve mechanisms that underlie memory format ion(1-3). Lip has been studied most extensively in the hippocampus, bu t the relation between hippocampal Lip and memory has been difficult t o establish(4-6). Here we explore the relation between LTP and memory in fear conditioning, an amygdala-dependent form of learning in which an innocuous conditioned stimulus (CS) elicits fear responses after be ing associatively paired with an aversive unconditioned stimulus (US). We have previously shown that Lip induction in pathways that transmit auditory CS information to the lateral nucleus of the amygdala (LA) i ncreases auditory-evoked field potentials in this nucleus(7). Now we s how that fear conditioning alters auditory CS-evoked responses in LA i n the same way as Lip induction, The changes parallel the acquisition of CS-elicited fear behaviour, are enduring, and do not occur if the C S and US remain unpaired. LTP-like associative processes thus occur du ring fear conditioning, and these may underlie the long-term associati ve plasticity that constitutes memory of the conditioning experience.