Multiple memory systems and extinction: the neurobiological basis of latent extinction

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Title: Multiple memory systems and extinction: the neurobiological basis of latent extinction
Author: Gabriele, Amanda
Abstract: Understanding the neural mechanisms underlying the extinction of maladaptive behaviors has become increasingly relevant . Extinction , or the reduction of a response due to lack of reinforcement , is believed to be ?new learning . ? Most extinction paradigms involve the performance of the previously reinforced response in the absence of reinforcement in order for extinction to occur . Conversely , latent extinction is a cognitive form of learning in which the previously rewarded response is not made during extinction training . However , until now the neurobiological basis of latent extinction has remained unknown . This dissertation has three aims to examine the neurobiological basis of latent extinction . Previous research has shown latent extinction to be impaired following hippocampal inactivation and the goal of Aim 1 was to examine other neural systems potentially involved in latent extinction through examination of brain structures such as the dorsal striatum , medial prefrontal cortex , and basolateral amygdala . Additionally , the neurochemical basis of latent extinction is unidentified ; therefore Aim 2 addressed this question , specifically investigating the glutamatergic system through both NMDA receptor agonism and antagonism . Finally , understanding latent extinction may be useful for the extinction of drug addiction . Aim 3 was to examine some clinical implications for the extinction of drug addiction utilizing latent extinction following maze running for an oral cocaine reward . Reversible neural inactivation studies using the sodium channel blocker bupivacaine demonstrated a selective impairment of response extinction following dorsal striatum inactivation , but no effect on either latent or response extinction following medial prefrontal cortex or basolateral amygdala inactivation . These results , coupled with previous data from our lab demonstrate a double dissociation for extinction behavior . Further , peripheral NMDA receptor agonism with D -cyloserine enhances latent extinction and intra -hippocampal NMDA receptor antagonism with AP5 impairs latent extinction , identifying a role for the glutamatergic system in latent extinction . Finally , oral cocaine administration during acquisition selectively impairs latent extinction indicating that drug use affects the relive use of multiple memory systems during extinction . Overall , the multiple memory systems theory and latent extinction provide a framework with which to further understand the neural mechanisms of extinction behavior .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2823
Date: 2009-05-15

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Multiple memory systems and extinction: the neurobiological basis of latent extinction. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2823 .

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