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Open Access Publications from the University of California

Amygdala processing of the formation and retrieval of cue-reward associations

  • Author(s): Tye, Kay M
  • Advisor(s): Doupe, Allison J
  • et al.
Abstract

This thesis examines the neural changes that contribute to the formation, storage, retrieval and extinction of a learned association between a stimulus and a reward. A number of questions were answered in this thesis to provide insight upon the neural substrates of several goal-directed behaviors: What neural changes mediate the initial formation of an associative memory between a stimulus and a reward? What are the synaptic changes that correspond to the development of a change in task-relevant neuronal firing? What is the mechanism of these synaptic changes, and do they have a causal relationship? How are complex emotions such as frustration represented in the brain? How are reward-associated cues endowed with the power to guide goal-directed behaviors in the absence of primary rewards? Here I show that behavior improves with the rapid recruitment of amygdala neurons to the ensemble encoding a reward-predictive cue, and that this change is mediated by the rapid strengthening of thalamic synapses onto amygdala neurons by a postsynaptic increase of AMPAR-mediated currents. These synaptic changes, in addition to the acquisition of the task, depend on NMDAR activation. Amygdala neurons that store the memory of a reward are activated when an animal compares the expected reward with the unexpected omission of that reward. Finally, distinct populations of amygdala neurons reflect the motivating and reinforcing properties of a cue endowed with the emotional significance to guide behavior.

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