Christopher Thomas Smith

Christopher Thomas Smith
Vanderbilt University | Vander Bilt · Department of Psychology

PhD

About

31
Publications
2,754
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455
Citations
Introduction
I am interested in understanding the neural mechanisms of choice behavior and other executive processes. Using behavioral genetic and neuroimaging techniques, I hope to better understand how choice preferences are encoded in the brain and the role of neural modulators in shaping these processes. Understanding choice behavior and how it can go awry has implications for why individuals make irrational choices in their daily lives and the poor choices seen in psychopathologies like drug addiction.
Additional affiliations
May 2009 - June 2014
University of North Carolina at Chapel Hill
Position
  • PhD Student
Description
  • Dissertation work focused on understanding the neural and biological bases of delay discounting behavior, its potential role as an intermediate phenotype for alcohol use disorders, and the role of prefrontal dopamine in modulating this behavior.

Publications

Publications (31)
Article
Full-text available
Dopamine function is broadly implicated in multiple neuropsychiatric conditions believed to have a genetic basis. Although a few positron emission tomography (PET) studies have investigated the impact of single-nucleotide polymorphisms (SNPs) in the dopamine D2 receptor gene (DRD2) on D2/3 receptor availability (binding potential, BP ND), these stu...
Article
Full-text available
Excessively choosing immediate over larger future rewards, or delay discounting (DD), associates with multiple clinical conditions. Individual differences in DD likely depend on variations in the activation of and functional interactions between networks, representing possible endophenotypes for associated disorders, including alcohol use disorders...
Article
Rate of delivery of psychostimulants has been associated with their positive euphoric effects and potential addiction liability. However, information on individual differences in onset of d-amphetamine’s effects remains scarce. We examined individual differences in the time to peak subjective and physiological effects and the pharmacokinetics/pharm...
Article
Full-text available
Adults with alcohol use disorders (AUDs) show marked immediate reward selection (or “Now”) bias in intertemporal choice tasks. This Now bias persists long into abstinence, suggesting an irreversible consequence of chronic alcohol abuse or a pre-existing AUD intermediate phenotype. However, some data show substantial Now bias among emerging adults (...
Preprint
Full-text available
People regularly give in to daily temptations in spite of conflict with personal goals. To test hypotheses about neuropharmacological influences on self-control, we used positron emission tomography to measure dopamine D2-like receptors (D2R) and experience sampling surveys to naturalistically track daily desires outside the laboratory in everyday...
Article
The evidence that dopamine function mediates the association between aging and cognition is one of the most cited findings in the cognitive neuroscience of aging. However, few and relatively small studies have directly examined these associations. Here we examined correlations among adult age, dopamine D2-like receptor (D2R) availability, and cogni...
Article
Full-text available
Theories of adult brain development, based on neuropsychological test results and structural neuroimaging, suggest differential rates of age‐related change in function across cortical and subcortical sub‐regions. However, it remains unclear if these trends also extend to the aging dopamine system. Here we examined cross‐sectional adult age differen...
Article
Full-text available
Rationale Sex differences in the dopaminergic response to psychostimulants could have implications for drug abuse risk and other psychopathology involving the dopamine system, but human data are limited and mixed. Objectives Here, we sought to investigate sex differences in dopamine release after oral d-amphetamine administration. Methods We used...
Preprint
Full-text available
The evidence that dopamine function mediates the association between aging and cognition is one of the most widely cited findings in the cognitive neuroscience of aging. However, relatively few and relatively small studies have directly examined these associations. Here we examined correlations among adult age, dopamine D2-like receptor (D2R) avail...
Article
Full-text available
Impulsivity is a transdiagnostic feature of a range of externalizing psychiatric disorders. Preclinical work links reduced ventral striatal dopamine transporter (DAT) availability with heightened impulsivity and novelty seeking. However, there is a lack of human data investigating the relationship between DAT availability, particularly in subregion...
Article
Full-text available
Some people are more willing to make immediate, risky, or costly reward-focused choices than others, which has been hypothesized to be associated with individual differences in dopamine (DA) function. In two studies using PET imaging, one empirical (Study 1: N = 144 males and females across 3 samples) and one meta-analytic (Study 2: N = 307 across...
Preprint
Full-text available
Some people are more willing to make immediate, risky, or costly reward-focused choices than others, which has been hypothesized to be associated with individual differences in dopamine (DA) function. In two studies using PET imaging, one empirical (Study 1: N=144 males and females across 3 samples) and one meta-analytic (Study 2: N=307 across 12 s...
Preprint
Full-text available
Theories of adult brain development, based on neuropsychological test results and structural neuroimaging, suggest differential rates of age-related change in function across cortical and subcortical sub-regions. However, it remains unclear if these trends also extend to the aging dopamine system. Here we examined cross-sectional adult age differen...
Article
The nigrostriatal and mesocorticolimbic dopamine networks regulate reward-driven behavior. Regional alterations to mesolimbic dopamine D2/3receptor expression are described in drug-seeking and addiction disorders. Parkinson’s disease (PD) patients are frequently prescribed D2-like dopamine agonist (DAgonist) therapy for motor symptoms, yet a propor...
Data
The supplementary data section provides 1.) PET acquisition parameters; 2.) a full description of mean ROI volume and BPnd values; 3.) a measure of effect size for all ROI-based analyses; 4.) standard-space ROI visualization and standard-space ROI BPnd scatterplots; 5.) visualization of supplementary whole-brain voxel-wise analysis considering PD s...
Article
Full-text available
Parkinson's disease (PD) is characterized by widespread degeneration of monoaminergic (especially dopaminergic) networks, manifesting with a number of both motor and non-motor symptoms. Regional alterations to dopamine D2/3 receptors in PD patients are documented in striatal and some extrastriatal areas, and medications that target D2/3 receptors c...
Article
Full-text available
Evidence suggests that dopamine levels in the prefrontal cortex (PFC) modulate executive functions. A key regulator of PFC dopamine is catechol-O-methyltransferase (COMT). The activity level of the COMT enzyme are influenced by sex and the Val 158 Met polymorphism (rs4680) of the COMT gene, with male sex and Val alleles both being associated with h...
Article
The fat mass and obesity associated gene (FTO) was the first gene identified by genome-wide association studies to correlate with higher body mass index (BMI) and increased odds of obesity. FTO remains the locus with the largest and most replicated effect on body weight, but the mechanism whereby FTO affects body weight and the development of obesi...
Article
Full-text available
The relatively modest spatial resolution of positron emission tomography (PET) increases the likelihood of partial volume effects such that binding potential (BPnd) may be underestimated. Given structural grey matter losses across adulthood, partial volume effects may be even more problematic in older age leading to overestimation of adult age diff...
Article
Full-text available
Converging evidence links individual differences in mesolimbic and mesocortical dopamine (DA) to variation in the tendency to choose immediate rewards ("Now") over larger, delayed rewards ("Later"), or "Now bias". However, to date, no study of healthy young adults has evaluated the relationship between Now bias and DA using positron emission tomogr...
Article
Full-text available
A variety of evidence suggests that, among humans, the individual tendency to choose immediate rewards ("Now") over larger, delayed rewards ("Later"), or Now bias, varies with frontal dopamine (DA) levels. As cyclic elevations in estradiol (E+) modulate other frontal DA-dependent behaviors, we tested ovarian cycle effects on Now bias, and whether a...
Article
Full-text available
The catechol-O-methyltransferase (COMT) enzyme has been widely studied due to its multiple roles in neurological functioning, estrogen biology, and methylation metabolic pathways. Numerous studies have investigated variation in the large COMT gene, with the majority focusing on single nucleotide polymorphisms (SNPs). This body of work has linked CO...
Article
Full-text available
Frontal-dependent task performance is typically modulated by dopamine (DA) according to an inverted-U pattern, whereby intermediate levels of DA signaling optimizes performance. Numerous studies implicate trait differences in DA signaling based on differences in the catechol-O-methyltransferase (COMT) gene in executive function task performance. Ho...
Article
Full-text available
A form of impulsivity, the tendency to choose immediate over delayed rewards (delay-discounting) has been associated with a single nucleotide polymorphism (SNP) in the catechol-O-methyltransferase (COMT) gene (COMTval¹⁵⁸met; rs4680). However, the existing data regarding the nature of this association are in conflict. We have previously reported tha...

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