Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item The Impact of Motor Learning on Motor Behavior and Cortical Dynamics in a Complex Stressful Social Environment(2016) Saffer, Mark Ian; Hatfield, Bradley; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)An economy of effort is a core characteristic of highly skilled motor performance often described as being effortless or automatic. Electroencephalographic (EEG) evaluation of cortical activity in elite performers has consistently revealed a reduction in extraneous associative cortical activity and an enhancement of task-relevant cortical processes. However, this has only been demonstrated under what are essentially practice-like conditions. Recently it has been shown that cerebral cortical activity becomes less efficient when performance occurs in a stressful, complex social environment. This dissertation examines the impact of motor skill training or practice on the EEG cortical dynamics that underlie performance in a stressful, complex social environment. Sixteen ROTC cadets participated in head-to-head pistol shooting competitions before and after completing nine sessions of skill training over three weeks. Spectral power increased in the theta frequency band and decreased in the low alpha frequency band after skill training. EEG Coherence increased in the left frontal region and decreased in the left temporal region after the practice intervention. These suggest a refinement of cerebral cortical dynamics with a reduction of task extraneous processing in the left frontal region and an enhancement of task related processing in the left temporal region consistent with the skill level reached by participants. Partitioning performance into ‘best’ and ‘worst’ based on shot score revealed that deliberate practice appears to optimize cerebral cortical activity of ‘best’ performances which are accompanied by a reduction in task-specific processes reflected by increased high-alpha power, while ‘worst’ performances are characterized by an inappropriate reduction in task-specific processing resulting in a loss of focus reflected by higher high-alpha power after training when compared to ‘best’ performances. Together, these studies demonstrate the power of experience afforded by practice, as a controllable factor, to promote resilience of cerebral cortical efficiency in complex environments.Item A PROGRAMMATIC RESEARCH APPROACH TO UNDERSTANDING THE IMPACT OF TEAM ENVIRONMENT ON CEREBRAL CORTICAL DYNAMICS AND ATTENTION(2012) Miller, Matthew Walker; Hatfield, Bradley D; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation describes a programmatic research approach to understanding how team environments alter individuals' brain dynamics so as to produce variations in individuals' cognitive-motor performances. This research is of fundamental interest as humans frequently perform in team environments. Specifically, the central purpose of this research was to determine if adaptive team environments are conducive to efficient brain dynamics such that tasks are accomplished with minimal neural costs. The dissertation is comprised of four studies (papers), each of which makes a unique contribution to the dissertation's central objective. The first paper reports a positive directional relationship between cerebral cortical activation as well as networking and task load. The second paper describes a new neurophysiological method for indexing attentional reserve, which is positively related to the efficiency of cerebral cortical activation and networking. The third paper describes the development of a paradigm employed to investigate the impact of team environment on neurocognitive functioning. This study used non-physiological techniques to index neurocognitive functioning while participants performed a cognitive-motor task in various team environments. Results suggest that, relative to neutral environments, maintaining performance in maladaptive team environments comes at a neurocognitive cost, while adaptive team environments enhance performance without such a cost. The final study applied the neurophysiological methods described in the first two studies to the team environment paradigm employed in the third study to provide neurobiological evidence in support of the conclusions reached in the third paper. Additionally, the final paper provides insight into the neurobiological changes underlying the alterations in neurocognitive functioning and task performance reported in the third paper. Specifically, the final paper reports that, relative to neutral environments, maintaining performance in maladaptive team environments comes at the expense of the efficiency of cerebral cortical activation and attentional reserve, while adaptive team environments enhance performance without such costs. Additionally, the final paper suggests that adaptive team environments may generate more optimal states of arousal, leading to performance enhancement. By comprehending the impact of team environments on brain dynamics, humans performing as members of teams in a variety of settings may be better equipped to maximize their performances.