Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item Medial Frontal Theta Negativities (MFTN) as Predictors of Anxiety Sensitivity Treatment Response(2019) Ellis, Jessica Steward; Bernat, Edward M; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anxiety is one of the most prevalent mental health problems around the world. Despite a number of widely available interventions, it can take weeks or months to see effects, and nearly half of individuals may not respond. In an effort to better understand response rates, a large body of evidence indicates the most consistent predictor of treatment outcomes is activity in the anterior cingulate cortex (ACC). Although activity in ACC can be measured by medial frontal theta event related potentials (ERPs) at a finer temporal resolution, these neurophysiological components have not been evaluated as predictors of treatment response. There is also a lack of research on the functional networks associated with ACC treatment prediction, despite implications for prefrontal engagement of cognitive control processes. The present study aimed to examine these gaps in the literature by using task-based electroencephalography (EEG) and medial frontal theta negativities (MFTN) as predictors of anxiety sensitivity treatment response. Using amplitude as well as functional connectivity measures (i.e., inter-channel phase synchrony), baseline MFTN (i.e., Theta-FN, Theta-N2) were assessed as predictors of treatment response at mid-treatment, 1-week post treatment, and 6 months post treatment. Subjects underwent a baseline EEG before completing three sessions of a computerized cognitive behavioral intervention. Contrary to the hypothesis, findings revealed MFTN amplitude did not predict treatment response. However, medial to lateral prefrontal theta phase synchrony demonstrated significant prediction effects, such that lower phase synchrony was associated with greater symptom improvement at mid-treatment, 1-week post treatment, and 6 months post treatment. This effect was specific to certain task conditions (i.e., gain feedback and go stimuli), as well as to the combined anxiety and depression treatment group. Results demonstrated accuracy and consistency of treatment prediction, as well as incremental validity after controlling for self-report measures. Finally, results provide additional support for a convergent medial frontal theta process, and suggest that low engagement of regulatory and proactive control mechanisms may be predictive of better response to cognitive behavioral interventions. This work represents a novel finding that may contribute to the improvement in treatment efficacy by serving as a target for future interventions and individualized treatment selection.Item Effects of early and concurrent parenting and child cortisol reactivity on hippocampal structure and functional connectivity during childhood: A prospective, longitudinal study(2017) Blankenship, Sarah Louise; Dougherty, Lea R; Riggins, Tracy; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Offspring of depressed mothers are at increased risk for emotional and behavioral disorders and social impairment. One proposed mechanism of risk transmission is through exposure to maladaptive parenting styles, as depressed mothers display higher levels of hostility and lower levels of support than non-depressed mothers. Rodent models indicate that the early parenting environment programs the endogenous stress response system, the hypothalamic-pituitary-adrenal (HPA) axis, through a cascade of epigenetic processes, ultimately elevating levels of glucocorticoid stress hormones (i.e., cortisol in humans). Elevated cortisol levels have been linked to both structural and functional changes in the hippocampus, a medial temporal lobe structure implicated in regulation of the HPA axis and the pathophysiology of depressive disorders. Despite elucidation of the pathways through which parenting influences neurobiological development in rodents, research examining these associations in humans is only emerging. The present study aimed to translate the rodent literature by examining the effects of early and concurrent parenting on hippocampal structure and functional connectivity during childhood, with a specific emphasis on exploring the mediating role of cortisol reactivity, in a longitudinal sample of offspring of depressed mothers and a community comparison group. At 3-6 and 5-10 years, observational measures of parenting and children’s salivary cortisol responses to a laboratory stressor were assessed. At 5-10 years, children completed structural and resting-state functional MRI scans. Findings revealed timing- and region-dependent associations. Early positive parenting predicted larger hippocampal head volumes whereas concurrent positive parenting predicted smaller body volumes. Early cortisol reactivity predicted larger body volumes whereas concurrent cortisol reactivity predicted smaller tail volumes. Concurrent parenting (positive and negative) predicted hippocampus subregion connectivity with regions of the cerebellum. Early cortisol reactivity predicted increased hippocampal connectivity with the cuneus and regions of the cingulate gyrus. There was a significant indirect effect of greater T1 Negative Parenting on smaller left hippocampal tail volume through increased concurrent cortisol reactivity. Significant interactions with maternal depression were also observed. This research provides a necessary translation of the rodent literature and elucidates possible timing-dependent neurobiological pathways through which early experience may confer increased risk for poor outcomes in human offspring.Item EXPERIMENTAL MEASUREMENT OF BEHAVIORAL APPROACH MOTIVATION IN MAJOR DEPRESSIVE DISORDER(2015) SZCZEPANIK, JOANNA; LEJUEZ, CARL W; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Major Depressive Disorder (MDD) presents a significant public health challenge. Given the symptoms heterogeneity and widespread changes in brain structure and Function in MDD, there may be several subtypes of depression not sufficiently distinguished by current diagnostic criteria but important to recognize to improve clinical outcomes. One of the two core symptoms of MDD is `markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day' and is often referred to as anhedonia (DSM-IV, V). Anhedonia may have a variety of underlying causes such as not finding previously enjoyed activities appealing, lacking motivation to engage or reluctance to put forth necessary effort, and these processes may be quite unique and not differentiated by current assessment methods (Treadway & Zald, 2011). It has been long recognized that depression is associated with insufficient environmental reinforcement (Peter M. Lewinsohn & Graf, 1973) and treatments were developed to address this deficiency (Peter M. Lewinsohn, Sullivan, & Grosscup, 1980). Clinical studies of effectiveness of the Behavioral Activation Treatment for Depression (BATD), (Hopko, Lejuez, LePage, Hopko, & McNeil, 2003), suggest that an increase in the engagement in reinforcing activities may be helpful in treatment of depression. However, a crucial aspect of activity related behavior, the initial approach and engagement which necessarily precede potential experience of enjoyment, has not been sufficiently characterized. In the current work, we present the development of an experimental behavioral approach motivation paradigm (BAMP) to study approach motivation to engage in liked activities, and relate experimental results to the symptoms of depression and anhedonia to better characterize approach behavior in MDD. We sought to establish a valid behavioral measure of approach motivation in major depression that will be suitable for behavioral and neuroimaging studies of anhedonia. In the BAMP study, subjects rated activity words for the appetitive value, and later `approached' and `avoided' the stimuli in an implicit joystick task. The findings indicated reduced range of activities rated as liked by depressed patients versus healthy controls, but no difference on an approach measure of liked activities. The depressed group showed a stronger approach rather than avoidance of disliked activities. Thus, `lack of interest or pleasure' may be partially related to excessive approach of mood-maintaining negative experiences, and inadequate avoidance of disliked situations. Further study of altered approach and avoidance behavior could shed additional light on processes underlying anhedonia in Major Depressive Disorder.