Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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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.Item Psychophysiological investigation of attentional processes during motor learning(2011) Rietschel, Jeremy Carl; Hatfield, Bradley D; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)As one becomes more proficient at a motor task the attentional demand required to perform that task decreases. Behavioral evidence suggests that experienced individuals possess greater attentional reserve during task execution compared to novices, such that, they are better able to cope with additional, possibly unexpected, challenges. This advantage may be the result of streamlining the neural processes underlying motor planning and execution over the course of learning. Such psychomotor efficiency reduces the demand on cortical resources imposed by the primary task such that they are available for coping with challenge beyond that of the task. However, this hypothesis has not been tested. The aim of this study was to provide neurobiological evidence of the positive relationship between motor skill and attentional reserve. Twenty-one participants were randomly assigned to one of two groups, a group that learned a novel visuomotor distortion task, and a control group that performed the same task with no distortion (i.e., no learning). For the duration of the task, event-related brain potentials (ERPs) elicited by a set of novel stimuli were recorded. The dynamic modulation of ERP component amplitude was used as an index of attentional reserve. We predicted that component amplitudes would initially be diminished in the learning group relative to the control group, but that there would be a progressive increase in amplitude as a function of learning; by contrast, we predicted that ERP component amplitudes would remain relatively stable in the control group. Importantly, task performance, as measured by initial directional error, was initially worse in the learning group relative to control group and significantly improved over the course of exposure, whereas the control group's performance was stable. This suggests the visuomotor distortion task employed was successful in serving as a model of motor skill acquisition. Analyses of the ERPs elicited by the auditory probes revealed that the exogenous components, N1 and P2, were not different between the two groups and did not change over the course of learning suggesting that early sensory processing was comparable between the two groups. Notably, the novelty P3 component-an index of the involuntary orienting of attention--was initially attenuated in the learning group relative to the control group, but progressively increased in amplitude as a function of learning in the learning group only. This suggests that attentional reserve increased as a function of motor skill acquisition, such that greater attentional resources were available to process the auditory probes. The current study provides psychophysiological evidence that attentional reserve increases as a function of motor skill acquisition. Moreover, the metric developed for this study provides a means to assess cognitive/motor learning in both applied cognitive and clinical domains.