Browsing by Subject "Functional Connectivity"

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    Investigating the Neural Networks Involved in Externalizing and Conscientious Behavior
    (2019-06) Rueter, Amanda Rae
    Conscientiousness and impulsivity are traits that affect how well an individual is able to achieve their goals. Individuals high in Conscientiousness are described as being more industrious, maintaining order in their life, and having high self-discipline (Ozer & Benet-Martínez, 2006) and would likely score low on disinhibited externalizing. Individuals who score high on disinhibited externalizing behavior show lack of constraint, have higher sensation seeking behavior and are more prone to substance use (Miller, Lynam, & Jones, 2008). However, the neural systems underlying variation in these traits are not well understood. Functional connectivity is a way to study neural networks of the brain and can be used to assess whether or not individual differences are associated with connectivity in the brain. Previous research shows positive associations between Conscientiousness and functional connectivity in the goal priority network (GPN; Rueter et al., 2018). Few studies have investigated associations between functional connectivity and Conscientiousness and disinhibited externalizing. In this dissertation, I: (1) attempted to replicate findings from a previous study with a larger sample to investigate associations between connectivity and Conscientiousness while extending the analysis to include disinhibited externalizing behavior and (2) apply the same functional connectivity methodology to a task-based fMRI data set to see if the traits of interest and connectivity remain associated during a cognitive task requiring inhibition. I hypothesized that the GPN and the central executive network (CEN) would be negatively associated with disinhibited externalizing behavior and that only the GPN would be positively associated with Conscientiousness. Results from study one and study two suggest that the CEN is negatively associated with disinhibited externalizing, while only study two suggests that the GPN is negatively associated with disinhibited externalizing. Study two supported the hypothesis that the GPN is associated with Conscientiousness, while Study 1 did not. This dissertation provides an integrated investigation of how Conscientiousness and externalizing behavior are related on a biological level. Resisting impulses and orienting oneself towards goals are both important behaviors implicated in successfully navigating life. Further research on these networks may help us create therapies or treatments to increase Conscientiousness and reduce self-compromising, maladaptive, externalizing behaviors.
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    Testing the effects of adolescent alcohol use on adult conflict-related theta dynamics
    (2017-02) Harper, Jeremy
    While adolescent alcohol use (AAU) has been associated with poor neurocognitive outcomes, few studies have utilized prospective samples, leaving uncertain any potential long-term neurocognitive effects of AAU. In addition, despite theoretical models linking AAU to diminished cognitive control, empirical work testing the relationship between AAU and specific neural correlates of cognitive control remains scarce. Recent work indicates that demands of cognitive control (e.g., response conflict) involve EEG theta-band dynamics, including medial frontal cortex (MFC) power and MFC-dorsal prefrontal cortex (dPFC) functional connectivity, which may be related to AAU-related neurocognitive dysfunction. The present study tested the hypothesis that greater AAU is associated with diminished adult conflict-related EEG theta-band dynamics in a large (N = 718) population-based prospective twin sample assessed at the target ages of 11, 14, 17, and 29. Two complementary analytic methods (cotwin control design; bivariate biometric modeling) were used to disentangle the genetic/shared environmental premorbid risk towards AAU from the potentially causal nonshared environmental effects of alcohol exposure. AAU was negatively associated with adult (age 29) theta MFC power and MFC-dPFC connectivity during a flanker task, suggesting that early drinking is associated with diminished cognitive control-related theta dynamics in adulthood. Both the CTC and biometric modeling results indicated that genetic influences primarily accounted for the association between AAU and reduced theta-band dynamics. Taken together, these findings suggest that the link between AAU and diminished adult cognitive control-related theta dynamics is likely a consequence of heritable genetic factors, rather than causal nonshared environmental effects.