The goal of this research project is to determine the involvement of the basolateral amygdala (BLA) in modulating the strength of physiological memory in the cerebral cortex, as indexed by learning-induced receptive field (RF) plasticity in the primary auditory cortex (ACx). The proposed experiments will investigate the role of the BLA in the induction and consolidation of RF plasticity. Moreover, the research will examine the involvement of the cholinergic nucleus basalis (NB) in mediating the BLA effects on cortical plasticity. It is well established that learning produces highly systematic changes in acoustic frequency receptive fields in the primary auditory cortex. Tuning is altered to increase response to and representation of behaviorally important stimuli (e.g., CS in classical conditioning) while reducing responses to other frequencies. RF plasticity has major characteristics of memory: it is associative, highly specific, rapidly induced, long-lasting (months) and exhibits consolidation, that is, increases in strength over hours and days. A central issue addressed by the proposed studies is whether the BLA modulates learning-induced cortical RF plasticity. There is extensive evidence that the BLA modulates the consolidation of memory for various kinds of training and that the modulation involves BLA influences on other brain regions including the caudate nucleus, hippocampus and entorhinal cortex. In view of the extensive evidence that the BLA modulates memory processes in other brain regions, including cortical regions, the proposed experiments will examine the role of the BLA in modulating the induction and consolidation of RF plasticity in the auditory cortex and determine whether the modulatory influences are mediated by activation of the NB. The findings will provide significant new information concerning the pathways and systems mediating the regulating influence of the BLA on memory consolidation and, thus, increase understanding of brain systems modulating the formation of memory for significant experiences.
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