Multidimensional coding by neurons of the basolateral amygdala and prefrontal cortex
Description
TitleMultidimensional coding by neurons of the basolateral amygdala and prefrontal cortex
Date Created2020
Other Date2020-10 (degree)
Extent1 online resource (xi, 110 pages)
DescriptionThe medial prefrontal cortex (mPFC) and basolateral complex of the amygdala (BLA), consisting of the lateral (LA), and basolateral (BL) and basomedial nuclei, are two nodes involved in the regulation of emotional memories. Specifically, BLA is involved in the acquisition and expression of conditioned responses (CRs) to stimuli (CSs) that predict aversive or appetitive outcomes. These CRs are thought to result from the activation of specific subsets of valence-coding BLA neurons. Under this model, the responses of BLA cells to CSs and the activity that drives CRs are closely related. In the third chapter of this thesis, I tested this hypothesis using a novel paradigm that dissociates BLA activity related to CS responses and CRs. At odds with this model, the CS responses and CR-related activity of individual BLA cells were separable. Moreover, while the incidence of valence-coding cells did not exceed chance, at the population level there was similarity between valence coding for CSs and CRs. In fact, both LA and BL neurons concurrently encoded multiple task features and behaviors.
The mPFC forms dense reciprocal connections with the BLA and has been shown to serve similar functions as the BLA in fear and reward conditioning. Additionally, these two brain regions have common cortical, striatal, and brainstem connections involved in emotional expression, neuromodulation, and autonomic regulation. Hence, to understand the overlapping and separable roles of the mPFC and BLA in appetitive and aversive conditioning, in the fourth chapter of this thesis, I recorded cells in both regions and compared their coding properties. Several similarities were apparent, including the proportions of stimulus and behavior responsive cells. However, mPFC neurons had more selective coding especially in relation to CRs evoked by different CSs. Importantly, neurons in the two structures encoded the same task features but to different degrees, leading to gradients of task representations. While PL and BL neurons represented many task variables through small fluctuations in their firing rates, LA cells coded fewer task features with stronger changes in activity. Population analyses revealed that while valence could be decoded from the activity of BLA and PL neurons, PL neurons were superior at distinguishing trial identity information. Thus, PL neurons have greater representational capacity than BLA neurons. The significance of these differences for the regulation of emotional memories is discussed.
NotePh.D.
NoteIncludes bibliographical references
Genretheses, ETD doctoral
LanguageEnglish
CollectionGraduate School - Newark Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.