Genetics, drugs, and cognitive control: uncovering individual differences in substance dependence

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dc.contributor.author Baker, Travis Edward
dc.date.accessioned 2012-09-11T20:14:42Z
dc.date.available 2012-09-11T20:14:42Z
dc.date.copyright 2012 en_US
dc.date.issued 2012-09-11
dc.identifier.uri http://hdl.handle.net/1828/4265
dc.description.abstract Why is it that only some people who use drugs actually become addicted? In fact, addiction depends on a complicated process involving a confluence of risk factors related to biology, cognition, behaviour, and personality. Notably, all addictive drugs act on a neural system for reinforcement learning called the midbrain dopamine system, which projects to and regulates the brain's system for cognitive control, called frontal cortex and basal ganglia. Further, the development and expression of the dopamine system is determined in part by genetic factors that vary across individuals such that dopamine related genes are partly responsible for addiction-proneness. Taken together, these observations suggest that the cognitive and behavioral impairments associated with substance abuse result from the impact of disrupted dopamine signals on frontal brain areas involved in cognitive control: By acting on the abnormal reinforcement learning system of the genetically vulnerable, addictive drugs hijack the control system to reinforce maladaptive drug-taking behaviors. The goal of this research was to investigate this hypothesis by conducting a series of experiments that assayed the integrity of the dopamine system and its neural targets involved in cognitive control and decision making in young adults using a combination of electrophysiological, behavioral, and genetic assays together with surveys of substance use and personality. First, this research demonstrated that substance dependent individuals produce an abnormal Reward-positivity, an electrophysiological measure of a cortical mechanism for dopamine-dependent reward processing and cognitive control, and behaved abnormally on a decision making task that is diagnostic of dopamine dysfunction. Second, several dopamine-related neural pathways underlying individual differences in substance dependence were identified and modeled, providing a theoretical framework for bridging the gap between genes and behavior in drug addiction. Third, the neural mechanisms that underlie individual differences in decision making function and dysfunction were identified, revealing possible risk factors in the decision making system. In sum, these results illustrate how future interventions might be individually tailored for specific genetic, cognitive and personality profiles. en_US
dc.language English eng
dc.language.iso en en_US
dc.subject substance dependence en_US
dc.subject event-related brain potentials en_US
dc.subject reward positivity en_US
dc.subject midbrain dopamine en_US
dc.subject reinforcement learning en_US
dc.subject cognitive control en_US
dc.subject genetics en_US
dc.subject personality risk factors en_US
dc.subject individual differences en_US
dc.subject anterior cingulate cortex en_US
dc.subject basal ganglia en_US
dc.subject probabalistic selection task en_US
dc.subject decision making en_US
dc.title Genetics, drugs, and cognitive control: uncovering individual differences in substance dependence en_US
dc.type Thesis en_US
dc.contributor.supervisor Holroyd, Clay Brian
dc.degree.department Dept. of Psychology en_US
dc.degree.level Doctor of Philosophy Ph.D. en_US
dc.rights.temp Available to the World Wide Web en_US
dc.identifier.bibliographicCitation Baker, T. E., Stockwell, T., Barnes, G., and Holroyd, C. B. (2011). Individual Differences in Substance Dependence: At the Intersection of Brain, Behaviour, and Cognition. Addiction Biology, 16, 458-466. en_US
dc.description.scholarlevel Graduate en_US

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