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Impact of Learning and Diet on Two Distinct Populations of Midbrain Dopamine Neurons

Wegener, Meredyth (2017) Impact of Learning and Diet on Two Distinct Populations of Midbrain Dopamine Neurons. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Dopamine is a crucial component of the neural mechanisms underlying motivation and reward learning, both of which are disrupted in psychiatric disorders. Much of the research in this field has focused on the role of ventral tegmental area (VTA) and its influence on the nucleus accumbens, but there is also evidence that the substantia nigra pars compacta (SNc), a separate dopaminergic region with its own efferent and afferent projections, contributes to guiding motivated behavior. Environmental insults, such as insufficient dietary nutrition, are thought to negatively impact the dopamine system and possibly promote the development of mental illness. These issues have not yet been investigated in the context of dopamine neuronal function during reward-mediated behavior. This dissertation sought to address this gap in our knowledge through two primary objectives. Using electrophysiology in awake-behaving animals, the first aim was to simultaneously record neuronal activity in the VTA and SNc during two reward-related associative learning paradigms to understand the role each region plays in motivated behavior. The second aim was to evaluate the impact of dietary deficiency on dopamine neuronal function and identify any region-specific effects in the VTA and SNc.
In our comparison of VTA and SNc, we employed an instrumental conditioning task, in which the animal executed a nose poke to earn a sugar pellet reward, and a Pavlovian conditioning task, which pairs a previously meaningless cue with a sugar pellet reward. We found that VTA and SNc may play similar roles in both forms of reward learning, possibly driven by common excitatory inputs between the two regions. We then measured correlations in activity of simultaneously recorded neurons within each region and found that how these correlations fluctuate in response to associative learning differed between regions. In our dietary manipulation experiment, we observed that event-evoked neuronal activity was reduced in animals lacking essential fatty acids, and this reduction is more pronounced in the SNc. Our findings suggest that the SNc may be more vulnerable to environmental insult and its role in reward learning and dysfunction in psychiatric disorders warrant further investigation.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Wegener, Meredythmaw201@pitt.edumaw201
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairGrace, Anthonygraceaa@pitt.edu
Committee MemberTurner, Robert
Committee MemberTorregrossa, Mary
Committee MemberCohen, Marlene
Committee MemberNapier, T Celeste
Committee MemberMoghaddam, Bita
Date: 28 September 2017
Date Type: Publication
Defense Date: 25 July 2017
Approval Date: 28 September 2017
Submission Date: 11 August 2017
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 153
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Neuroscience
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: electrophysiology n-3 PUFA Pavlovian Instrumental
Date Deposited: 29 Sep 2017 01:14
Last Modified: 13 Mar 2019 18:36
URI: http://d-scholarship.pitt.edu/id/eprint/33081

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