The role of cellular and chemical signaling within the nucleus accumbens in value-based decision making behaviors
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Sugam, Jonathan Adam. The Role of Cellular and Chemical Signaling Within the Nucleus Accumbens In Value-based Decision Making Behaviors. University of North Carolina at Chapel Hill, 2013. https://doi.org/10.17615/dc4f-dk30APA
Sugam, J. (2013). The role of cellular and chemical signaling within the nucleus accumbens in value-based decision making behaviors. University of North Carolina at Chapel Hill. https://doi.org/10.17615/dc4f-dk30Chicago
Sugam, Jonathan Adam. 2013. The Role of Cellular and Chemical Signaling Within the Nucleus Accumbens In Value-Based Decision Making Behaviors. University of North Carolina at Chapel Hill. https://doi.org/10.17615/dc4f-dk30- Last Modified
- March 22, 2019
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Sugam, Jonathan Adam
- Affiliation: College of Arts and Sciences, Department of Psychology and Neuroscience
- Abstract
- A critical component of an organism's survival is the ability to secure the necessary resources including food, shelter and mates. In order to make appropriate decisions to do so, animals must weigh the costs and benefits of different courses of action and choose the best available option. Importantly, these costs and benefits are rarely static, and organisms must attend to these changes in order to act appropriately. Multiple lines of research have identified that value-based decision making is mediated by a distributed network of brain nuclei including the nucleus accumbens (NAc) and its innervation from dopamine neurons located in the midbrain. However, the precise way in which this circuitry mediates value-based decision making remains unclear. The first set of experiments detailed in this dissertation used electrophysiological recording techniques to measure neural activity within the NAc during a risky decision making paradigm. These experiments revealed that a subset of NAc neurons tracked the different options available to the animal, displaying selective activity for risk versus safe options. Further, behavioral preferences to take a risk or play it safe were correlated with neural encoding of reward omissions. In the second set of experiments electrochemical procedures were used to evaluate the patterns of dopamine release that signal reward value as animals attend to changes in their environment and adjust their behavior accordingly. In these experiments, animals learned that cues predicted the availability of a smaller immediate reward or larger rewards delivered after varying delays. NAc dopamine concentration signaled the predicted value of the future outcome, and shifted as the relative value of the rewards changed. The final set of experiments evaluated possible causal links between phasic dopamine release and decision making using optogenetic methods. Animals displayed goal-directed behavior to receive optical stimulation of dopamine terminals, and adjusted their behavior as the intensity of stimulation changed. Further, stimulation of phasic dopamine release was sufficient to shift certain value-based decisions. Together, these experiments provide novel characterizations of the neural circuits and mechanisms by which value-based decisions are processed within the brain, providing insight into the potential role of the NAc and mesolimbic dopamine system in mediating appropriate decisions.
- Date of publication
- August 2013
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- In Copyright
- Advisor
- Carelli, Regina
- Degree
- Doctor of Philosophy
- Graduation year
- 2013
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