Browsing Ph.D. Psychology by Subject "event-related potentials"
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Affective Traits of Psychopathy and the Role of Early Visual Attention: An Electrophysiological StudyModels of affective processing abnormalities in psychopathy have involved both amygdala abnormalities and attentional deficits to peripheral affective information. Neurophysiological bases for the latter are not currently well understood. Often presented as competing explanations for affective traits of psychopathy, these models may instead be compatible, describing different levels of analysis, with the amygdala playing a role in early attention allocation. To explore this possibility, this dissertation was designed to integrate these two areas of the literature by proposing a neurophysiologically-based model of biases in attention to peripheral affective information in psychopathy. This model is centred on the idea that attentional biases seen in psychopathy may result from reduced responsivity of a subcortical thalamus-amygdala circuit that influences the allocation of attention to salient stimuli in the environment during initial stages of processing. Event-related potential (ERP) components that reflect attention allocation during early stages of visual information processing were used to test the hypothesis that individuals high in psychopathic traits would show reduced attention allocation to peripheral information in the form of reduced and/or delayed ERP responses. Explored were the relations between psychopathic personality traits and early ERP responses to simple stimulation of the visual system (Study 1) and to spatially-filtered emotional faces involving implicit versus explicit processing of the stimuli (Study 2). ERP effects related to overall psychopathic trait severity, but also yielded factor-specific ERP response patterns. Study 1 results were consistent with the present hypotheses. Specifically, higher Factor 1 scores (primary, affect-based traits) were associated with reduced attention-related ERP amplitudes in response to a flash stimulus presented peripheral to task performance. Factor 2 severity (secondary antisocial and behavioural traits) was associated with ERP latencies in primary visual cortex. Study 2 also showed somewhat more complex but Factor-specific patterns of early visual processing. Overall, the results were consistent with a reduced responsivity of the thalamo-amygdalar pathway in psychopathy-related individual differences in attention at early stages of visual information processing, both for affective information and simple sensory stimulation. This raises the question of whether such processing differences are a predisposing factor for the development of psychopathic traits.
Genetic and Electrophysiological Correlates of Self-Regulation in AdolescenceSelf-regulation is considered a powerful predictor of behavioral and mental health outcomes during adolescence and emerging adulthood. In this dissertation I address some electrophysiological and genetic correlates of this important skill set in a series of four studies. Across all studies event-related potentials (ERPs) were recorded as participants responded to tones presented in attended and unattended channels in an auditory selective attention task. In Study 1, examining these ERPs in relation to parental reports on the Behavior Rating Inventory of Executive Function (BRIEF) revealed that an early frontal positivity (EFP) elicited by to-be-ignored/unattended tones was larger in those with poorer self-regulation. As is traditionally found, N1 amplitudes were more negative for the to-be-attended rather than unattended tones. Additionally, N1 latencies to unattended tones correlated with parent-ratings on the BRIEF, where shorter latencies predicted better self-regulation. In Study 2 I tested a model of the associations between selfregulation scores and allelic variations in monoamine neurotransmitter genes, and their concurrent links to ERP markers of attentional control. Allelic variations in dopaminerelated genes predicted both my ERP markers and self-regulatory variables, and played a moderating role in the association between the two. In Study 3 I examined whether training in Integra Mindfulness Martial Arts, an intervention program which trains elements of self-regulation, would lead to improvement in ERP markers of attentional control and parent-report BRIEF scores in a group of adolescents with self-regulatory difficulties. I found that those in the treatment group amplified their processing of attended relative to unattended stimuli over time, and reduced their levels of problematic behaviour whereas those in the waitlist control group showed little to no change on both of these metrics. In Study 4 I examined potential associations between self-regulation and attentional control in a group of emerging adults. Both event-related spectral perturbations (ERSPs) and intertrial coherence (ITC) in the alpha and theta range predicted individual differences in self-regulation. Across the four studies I was able to conclude that real-world self-regulation is indeed associated with the neural markers of attentional control. Targeted interventions focusing on attentional control may improve self-regulation in those experiencing difficulties in this regard.