The Neural Substrates Supporting the Inhibition of Instrumental Avoidance Behavior
Burhans, Lauren B.
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Permalink
https://hdl.handle.net/2142/82500
Description
Title
The Neural Substrates Supporting the Inhibition of Instrumental Avoidance Behavior
Author(s)
Burhans, Lauren B.
Issue Date
2005
Doctoral Committee Chair(s)
Gabriel, Michael
Department of Study
Neuroscience
Discipline
Neuroscience
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Psychology, Behavioral
Language
eng
Abstract
Previous studies have elucidated much of the neural circuitry underlying the acquisition of discriminative avoidance behavior in rabbits, wherein rabbits learn to step in an activity wheel in response to a conditional stimulus (CS+) predictive of a foot shock while learning to avoid another stimulus (CS-) not followed by shock. However, less is know about the neural substrates involved in the inhibition of this behavior, as occurs when a stimulus acquires inhibitory properties and signals response omission. The following thesis aimed to uncover the neural substrates that underlie the inhibition of conditioned responding that occurs during extinction of discriminative avoidance behavior and during the acquisition of conditioned inhibition. The first study tested the hypothesis that the flow of information from the entorhinal cortex through the ventral subiculum to the nucleus accumbens is the pathway that mediates the suppression of conditioned responding in response to novel contextual cues during extinction of discriminative avoidance behavior. The results supported this hypothesis, demonstrating that lesions of the ventral subiculum disrupted the contextual specificity of both extinction behavior and extinction-related neuronal plasticity in the nucleus accumbens. A second study investigated the role of the amygdala in extinction learning by investigating the effects of amygdalar inactivation during extinction in a familiar or novel training context. The findings indicated a role for the amygdala in the contextual specificity of extinction memories and the initiation of extinction-related plasticity in cingulothalamic brain areas. A third study examined the neural correlates of conditioned inhibition by examining neuronal activity during instrumental feature-negative discrimination training. Results favored an early convergence model of conditioned inhibition, in which the encoding of conditioned inhibition manifests early in the stimulus processing stream in sensory and limbic areas.
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