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Characterization of the neural mechanisms supporting the implementation of cognitive control in human decision making

Citation

Hakimi, Shabnam (2014) Characterization of the neural mechanisms supporting the implementation of cognitive control in human decision making. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:10052013-125503107

Abstract

Humans are particularly adept at modifying their behavior in accordance with changing environmental demands. Through various mechanisms of cognitive control, individuals are able to tailor actions to fit complex short- and long-term goals. The research described in this thesis uses functional magnetic resonance imaging to characterize the neural correlates of cognitive control at two levels of complexity: response inhibition and self-control in intertemporal choice. First, we examined changes in neural response associated with increased experience and skill in response inhibition; successful response inhibition was associated with decreased neural response over time in the right ventrolateral prefrontal cortex, a region widely implicated in cognitive control, providing evidence for increased neural efficiency with learned automaticity. We also examined a more abstract form of cognitive control using intertemporal choice. In two experiments, we identified putative neural substrates for individual differences in temporal discounting, or the tendency to prefer immediate to delayed rewards. Using dynamic causal models, we characterized the neural circuit between ventromedial prefrontal cortex, an area involved in valuation, and dorsolateral prefrontal cortex, a region implicated in self-control in intertemporal and dietary choice, and found that connectivity from dorsolateral prefrontal cortex to ventromedial prefrontal cortex increases at the time of choice, particularly when delayed rewards are chosen. Moreover, estimates of the strength of connectivity predicted out-of-sample individual rates of temporal discounting, suggesting a neurocomputational mechanism for variation in the ability to delay gratification. Next, we interrogated the hypothesis that individual differences in temporal discounting are in part explained by the ability to imagine future reward outcomes. Using a novel paradigm, we imaged neural response during the imagining of primary rewards, and identified negative correlations between activity in regions associated the processing of both real and imagined rewards (lateral orbitofrontal cortex and ventromedial prefrontal cortex, respectively) and the individual temporal discounting parameters estimated in the previous experiment. These data suggest that individuals who are better able to represent reward outcomes neurally are less susceptible to temporal discounting. Together, these findings provide further insight into role of the prefrontal cortex in implementing cognitive control, and propose neurobiological substrates for individual variation.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:cognitive control, decision making, fMRI, intertemporal choice, prefrontal cortex, response inhibition
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Computation and Neural Systems
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • O'Doherty, John P.
Thesis Committee:
  • Adolphs, Ralph (chair)
  • Camerer, Colin F.
  • O'Doherty, John P.
  • Perona, Pietro
  • Shimojo, Shinsuke
Defense Date:14 August 2013
Non-Caltech Author Email:shabnamhakimi (AT) gmail.com
Record Number:CaltechTHESIS:10052013-125503107
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:10052013-125503107
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7969
Collection:CaltechTHESIS
Deposited By: Shabnam Hakimi
Deposited On:09 Oct 2013 16:33
Last Modified:09 Oct 2013 16:33

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