Title page for ETD etd-05182017-120942


Type of Document Master's Thesis
Author Feng, Shengchuang
Author's Email Address scfeng@vt.edu
URN etd-05182017-120942
Title Association between Reward Sensitivity and Smoking Status in Major Depressive Disorder
Degree Master of Science
Department Psychology
Advisory Committee
Advisor Name Title
Brooks King-Casas Committee Chair
Jian Li Committee Member
Pearl H. Chiu Committee Member
Keywords
  • fMRI
  • depression
  • nicotine
  • prediction error
  • dopamine
  • reward sensitivity
Date of Defense 2017-05-10
Availability unrestricted
Abstract
Chronic nicotine use has been linked to increased sensitivity to nondrug rewards as well as improvement in mood among individuals with depression, and these effects have been hypothesized to be mediated through alternations in striatal dopamine activity. Similarly, chronic nicotine use is hypothesized to influence the mechanisms by which healthy and depressed individuals learn about rewards in their environment. However, the specific behavioral and neural mechanisms by which nicotine influences the learning process is poorly understood. Here, we use a probabilistic learning task, functional magnetic resonance imaging and neurocomputational analyses, to show that chronic smoking is associated with higher reward sensitivity, along with lower learning rate and striatal prediction error signal. Further, we show that these effects do not differ between individuals with and without major depressive disorder (MDD). In addition, a negative correlation between reward sensitivity and striatal prediction error signal was found among smokers, consistent with the suggestion that enhanced tonic dopamine associated with increased reward sensitivity leads to an attenuation of phasic dopamine activity necessary for updating of reward value during learning.
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