Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item Developmental Parsing and Cognitive Control(2022) Ovans, Zoe; Huang, Yi Ting; Novick, Jared; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Processing sentences incrementally entails making commitments to structure (and sometimes role assignments) before all information in a sentence is present. Children in particular have been shown to have difficulty revising the initial structural commitments they make when these turn out to be incorrect (Trueswell et al., 1999; Hurewitz et al., 2000; Weighall, 2008; Choi & Trueswell, 2010; Anderson et al., 2011). While prior research has generally ascribed this to limitations in the development of children’s non-linguistic cognitive-control system, a precise account of how cognitive control limitations might lead to difficulty with incremental sentence processing is missing from the literature. In part, this is because existing research has focused on individual differences in children’s ability to exert cognitive control over their thoughts and actions. In contrast, this dissertation makes use of within-child variation in cognitive-control engagement to provide evidence that children’s domain-general cognitive-control system pushes them to rely more heavily on reliable parsing cues (and less heavily on unreliable ones) when the system is highly engaged. This conclusion brings together seemingly disparate results from child and adult conflict adaptation studies, where adults appear to adapt to conflict but children do not. Overall, it is concluded that cognitive-control engagement leads both children and adults to re-rank parsing cues to attend more to ones that are more task-relevant, but the criteria they use to determine which cues are most relevant can change with language experience.Item Development of Motivational Influences on Monitoring and Control Recruitment in the Context of Proactive and Reactive Control in Adolescent Males(2020) Bowers, Maureen; Fox, Nathan A; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Adolescence and the onset of puberty is a time period of physiological and behavioral changes that include a heightened reward sensitivity, but underdeveloped cognitive control. Cognitive control involves monitoring for salient stimuli and recruiting control to adapt behavior advantageously to reach a specific goal and is supported by the three domains of executive functioning (EF): inhibitory control, set-shifting, and working memory. Proactive control is engaged after an informative cue in preparation for an upcoming stimulus, while reactive control can be employed when preparation is not possible and you need to respond to a stimulus. Oscillations in the theta frequency (4-8Hz) during both cue presentation and stimulus presentation are implicated in proactive and reactive control processes. While reward has been shown to upregulate proactive control in adults, little work has assessed how reward influences theta oscillations during both proactive and reactive control throughout adolescence and pubertal development. Further, no work has sought to understand how EF abilities bolster reward-related changes in proactive or reactive control. Here, 68 adolescent males (Meanage=13.61, SDage=2.52) aged 9 – 17 years old completed a rewarded cued flanker paradigm while electroencephalogram (EEG) was collected. They also completed tasks from the NIH toolbox that tap the three EF domains. Behaviorally, reward hindered performance on proactive trials, particularly in mid-puberty, while enhancing performance on reactive trials. Reward was associated with increases in cue-locked theta power, but with overall reductions in cue-locked theta ICPS. Stim-locked theta power increased on reactive trials with increasing age, while stim-locked theta ICPS peaked in mid-adolescence for rewarded trials. Increased cue theta power was associated with worse performance on proactive trials. On proactive trials, adolescents with low levels of inhibitory control experience more reward-related interference, while reward-related interference was mitigated by better set-shifting abilities only in younger and older adolescents. In conclusion, reward differentially impacts proactive and reactive control throughout adolescent development and EF influences the impact of reward on proactive control throughout adolescence.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 Action and perception: Neural indices of learning in infants(2016) Yoo Chon, Kathryn Hye Jin; Fox, Nathan A; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Early human development offers a unique perspective in investigating the potential cognitive and social implications of action and perception. Specifically, during infancy, action production and action perception undergo foundational developments. One essential component to examine developments in action processing is the analysis of others’ actions as meaningful and goal-directed. Little research, however, has examined the underlying neural systems that may be associated with emerging action and perception abilities, and infants’ learning of goal-directed actions. The current study examines the mu rhythm—a brain oscillation found in the electroencephalogram (EEG)—that has been associated with action and perception. Specifically, the present work investigates whether the mu signal is related to 9-month-olds’ learning of a novel goal-directed means-end task. The findings of this study demonstrate a relation between variations in mu rhythm activity and infants’ ability to learn a novel goal-directed means-end action task (compared to a visual pattern learning task used as a comparison task). Additionally, we examined the relations between standardized assessments of early motor competence, infants’ ability to learn a novel goal-directed task, and mu rhythm activity. We found that: 1a) mu rhythm activity during observation of a grasp uniquely predicted infants’ learning on the cane training task, 1b) mu rhythm activity during observation and execution of a grasp did not uniquely predict infants’ learning on the visual pattern learning task (comparison learning task), 2) infants’ motor competence did not predict infants’ learning on the cane training task, 3) mu rhythm activity during observation and execution was not related to infants’ measure of motor competence, and 4) mu rhythm activity did not predict infants’ learning on the cane task above and beyond infants’ motor competence. The results from this study demonstrate that mu rhythm activity is a sensitive measure to detect individual differences in infants’ action and perception abilities, specifically their learning of a novel goal-directed action.