School of Public Health

Permanent URI for this communityhttp://hdl.handle.net/1903/1633

The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

Note: Prior to July 1, 2007, the School of Public Health was named the College of Health & Human Performance.

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Now showing 1 - 7 of 7
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    THE INFLUENCE OF CUMULATIVE SLEEP RESTRICTION ON HUMAN PERFORMANCE: EXAMINATION OF BRAIN DYNAMICS AND SUSTAINED ATTENTION
    (2024) Kahl, Steven; Hatfield, Bradley; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Sustained attention (SA) impacts nearly every aspect of human performance. From the exactness of performing brain surgery to safely driving from one location to another, the ability to concentrate on a task for a period of time is important for success in work, school, relationships, and individual activities. As a key component of executive function (EF) and psychomotor performance, SA can be affected by many mental and physical processes. One process that can impact SA is restricted sleep, which is becoming more relevant in our ever-evolving technological society. Numerous studies have examined the impact of short bouts of restricted sleep on response time, a measure of SA, but few studies have examined the impact of the accumulating effect of sleep restriction (SR) on response time and brain dynamics as measured with electroencephalography (EEG). As part of a larger 40-day study, eight healthy participants (five female, average age 27.75) were observed for seven consecutive days and nights in a sleep lab, where they spent five hours in bed per night and engaged in numerous psychomotor vigilance tests (PVT), an indicator of SA, as part of their daytime activities. Through multiple one-factor ANOVAs, response time significantly slowed, and brain dynamic changes occurred, measured by slow wave activity (SWA) maxima change in the Fz electrode, located in the midline frontal region, over the course of the entire week of continual SR compared to an extended sleep night. Employing mixed method effects revealed a statistically significant relationship between response time and SWA maxima differences. The data show that not only does response time increase the day after rising first and last SWA maxima levels converge (i.e., flattening of the line slope connecting these values) caused by short bouts of SR, but these phenomena continue this progression with prolonged SR. Over the course of the week-long SR, the final SWA maximum increased at a higher rate than the first SWA maximum, leading to the maxima difference shrinking as response time increases. These findings indicate that brain dynamics highlight less restorative sleep occurring alongside a lack of sustained attention when sleep is restricted on a consistent basis.
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    HACKING THE NERVOUS SYSTEM: PROMOTION OF PSYCHOMOTOR EFFICIENCY THROUGH VAGUS NEUROMODULATION
    (2021) Lu, Calvin; Hatfield, Bradley D; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Research in performance optimization aims to improve cognitive-motor performance under arduous conditions. From a kinesiology perspective, effectiveness in performance optimization can be quantified through the neurophysiological economy of goal-directed motor behavior. Derived from the psychomotor efficiency hypothesis, the cognitive-affective-motor (CAM) model discusses the brain's complex intersections of cognitive-motor and cognitive-affective processes. The CAM model subscribes to the principle that superior performance is achieved by minimizing nonessential motoric processes, such as mental stress management. When stress response becomes unmanageable, there will be an elevation in nonessential motoric processes and negatively impact motor preparation. The resulting disfluency within the central nervous system will ultimately manifest in the motor and autonomic sections of the peripheral nervous system. To combat the disruptive effects of mental stress, employing autonomic regulation techniques such as Vagus nerve neuromodulation can remedy the inefficiencies of the nervous systems and promote an adaptive state for performance. This dissertation aimed to assess the CAM model empirically by investigating the integrative model of the cortical, autonomic, and motor nervous systems during a precision motor task (i.e., dart-throwing). A thorough examination was conducted on preserving the nervous system’s efficiency and positive impacts on the quality of motor performance through Vagus nerve neuromodulations. Specifically, the study focused on varying levels of mental stress to determine inoculation capabilities. Twenty-three participants were enrolled in a repeated-measures within-subjects design. Neurophysiological measures of nervous system activity were captured before motor execution to determine the amalgamated influence of Vagus nerve neuromodulation and mental stress. The observed results revealed an elevation in psychomotor efficiency through the Vagus nerve neuromodulations. Participants exhibited improved performance, as seen through a reduction of accuracy variability. This was accompanied by nervous system alterations of increased left temporal alpha power, reduced motor unit engagements, and reduced mental workload during the preparation of motor execution. In summary, the observed effects of Vagus nerve neuromodulation techniques successfully promoted nervous system efficiency and an adaptive state for goal-directed motor behavior. The dissertation outcomes provide evidence on the benefits of ergonomic aids such as Vagus nerve neuromodulation on facilitating an adaptive nervous system to enhance cognitive-motor performance.
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    THE IMMEDIATE EFFECT OF VENTILATORY TRAINING ON HEART RATE VARIABILITY AND BRAIN DYNAMICS, DURING TRAINING AND CHALLENGE
    (2018) Lu, Calvin; Hatfield, Bradley D; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    A Guided Ventilatory Maneuver (GVM) can lead to changes in the central and autonomic nervous systems. Chronic effects of GVM have been reported in the literature to enhance physical and mental health. Purpose: To investigate the immediate effects of GVM on cortical activity and cardiovascular activity. Method: Twenty healthy participants (age 18-30) were recruited. Eligibility for the study required no experience in any mindfulness training. Results: Measures of the study utilized electroencephalography and electrocardiogram to measure cortical and cardiovascular changes. The study provided support for acute effects of GVM on cortical dynamics and heart rate variability. Cortical activity exhibited an increase in cortical relaxation during GVM. And cardiovascular activity exhibited an increase in parasympathetic activity. Conclusion: The psychophysiological measures of this study provided evidence for GVM as a relaxation technique. Specifically, during GVM, participant’s cortical dynamics reflect an increase in relaxation.
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    INVESTIGATIONS TO UNDERSTAND THE UNDERLYING BRAIN PROCESSES WHICH ENHANCE COGNITIVE-MOTOR LEARNING AND PERFORMANCE
    (2018) Jaquess, Kyle James; Hatfield, Bradley D; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The ability to effectively and efficiently process task-relevant information is a critical element to a wide range of cognitive-motor activities. Indeed, various studies have illustrated that elite performers exhibit more refined neuro-cognitive processes than novices. However, it is unclear how these neuro-cognitive information processing abilities develop as skill is acquired. In this dissertation, I provide some evidence to address this gap in the literature. Study 1, entitled “Empirical evidence for the relationship between cognitive workload and attentional reserve” (Jaquess et al., 2017), provided evidence illustrating the relationship between mental workload and attentional reserve. Study 2, entitled “Changes in mental workload and motor performance throughout multiple practice sessions under various levels of task difficulty”, builds from the knowledge gained from Study 1 and extends it to a cognitive-motor learning/practice context over the course of four days. Finally, Study 3, entitled “How engaged are you? An investigation of the neurocognitive mechanisms of self-controlled practice during cognitive-motor learning”, was built upon the knowledge gained from Study 2 to further investigate how aspects of the practice environment, specifically the aspect of control, impact cognitive load and learning outcomes. Broadly, these studies illustrate how some of the neuro-cognitive processes related to information processing in cognitive-motor skills, specifically elements of the electroencephalogram (EEG), change with learning and the acquisition of skill.
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    THE INFLUENCE OF CONSCIOUS CONTROL OF MOVEMENT ON BRAIN PROCESSES AND THE QUALITY OF COGNITIVE-MOTOR PERFORMANCE
    (2015) Lo, Li-Chuan; Hatfield, Bradley D.; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The impact of mental stress on fine motor performance is typically maladaptive. The current research was conducted to investigate the manner by which state anxiety affects performance using a cognitive neuroscience perspective. The basic proposition tested, derived from the Reinvestment Theory and the Psychomotor Efficiency Hypothesis, is that stress introduces neuromotor noise to motor planning processes that translate as excess recruitment of motor units and degrade performance. Electroencephalography (EEG) was employed in Study 1 to assess regional cortical activation and cortico-cortical communication between non-motor associative and motor planning regions during the preparatory period of a dart-throwing task. The task was performed during stress (i.e., social evaluation, monetary incentives, and threat of electrical shock) and a relatively relaxed control condition through a within-subjects design. Regional activation was estimated from bilateral EEG recordings in the frontal, central, temporal, parietal, and occipital regions via spectral analysis to assess low-alpha and high-alpha band power to determine generalized arousal and task-relevant attentional focus, respectively. Cortico-cortical communication was estimated between all bilateral regions and the frontal motor planning area with particular emphasis on the left temporal (T3) to midline frontal (Fz) coherence. Elevated state anxiety was induced and associated with heightened T3-Fz EEG connectivity and synchrony of high-alpha band in the right occipital region. Based on these findings, Study 2 was conducted to determine the psychological processes accounting for the observed elevation in T3-Fz EEG coherence and the quality of muscle action during the throwing task. Specifically, participants employed an internal and an external attentional focus to perform the throwing task while their EEG and electromyography (EMG) were monitored. The use of internal focus, which is consistent with explicit monitoring of movement mechanics, was predicted to result in elevated T3-Fz EEG connectivity. This prediction was supported and, furthermore, the magnitude of connectivity was positively associated with motor unit activity assessed via EMG of four major muscle groups (i.e., flexor carpi ulnaris, extensor carpi radialis, biceps brachii, and triceps brachii). The evidence provided supports the theoretical notion that explicit monitoring promotes inefficient muscle activity, which mediates to impact performance negatively.
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    THE EFFECTS OF AN ACUTE BOUT OF EXERCISE UPON BEHAVIORAL RESPONSES TO AND NEUROPHYSIOLOGICAL INDICES OF ATTENTION ALLOCATION IN CHILDREN AND ADULTS
    (2014) Cipriani, Kristin; Clark, Jane E.; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In both child and adult populations, engagement in frequent physical activity results in a myriad of cognitive benefits, including improved executive functioning. However, the relationship between engagement in acute bouts of physical activity and cognitive processes, such as attention allocation, are less well understood. Methods: This study sought to: 1) Investigate the effects of an acute bout of exercise on behavioral responses; 2) Investigate the effects of an acute bout of exercise on neurophysiological measures; and, 3) Investigate age-related differential effects. EEG was recorded from 32 male participants (n=16 adults, n=16 children 9-11 years of age) who completed a 3-stimulus auditory oddball behavioral task, pre- and post-exercise intervention. Results: Contrary to expectations, this study found that, regardless of age, engagement in an acute bout of exercise did not have a significant effect upon some behavioral and all neurophysiological indices of attention, as measured by response accuracy, reaction time percent difference, and P3a and P3b amplitude, respectively. Moreover, the findings indicate no age-related differential effects of acute exercise on these same indices of attention. However, absolute reaction time results indicate a significant main effect for group (F (1, 21) =4.48, p<0.05) in the block immediately following the acute exercise intervention. Discussion: The relative ease with which both adult and child participants completed the behavioral task indicates that the task may have been simple, rather than executive in nature. Therefore, only some of the behavioral benefits and none of the typical neurophysiological benefits associated with acute exercise bouts were seen in this study, nor were age-related differential effects of acute exercise observed. However, the significant difference in reaction time between intervention and control groups immediately following the intervention, does provide the behavioral results typical of this intervention. Future studies should explore similar acute exercise interventions in combination with a varied behavioral task (e.g., a modified 3-stimulus auditory oddball) that strongly activates the executive functioning network.
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    Arousal and skilled motor performance: The mediating role of cerebral cortical dynamics
    (2006-08-16) Rietschel, Jeremy Carl; Hatfield, Bradley D; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Despite achievement of a highly skilled level of motor competence, elucidation of the multiple factors contributing to variability of motor performance remains somewhat enigmatic. The inverted-U hypothesis posits moderate levels of arousal as essential to optimal performance; this suggests that arousal may be a key player of this variability. The purpose of this study was to examine the psychophysiological concomitants of moderate as compared to low arousal. Specifically we hypothesized a decrease in coherence between the temporal lobes (T3-verbal-analytical processing & T4-visuo-spatial processing) and the motor planning region (Fz), accompanied by an increase in task performance. Fifteen college undergraduates (9 females, 6 males, mean age = 23.4, SD = 4.22) participated in two days of testing. Day one consisted of 340 trials of a novel visuomotor pointing task to achieve task competency. On the second day, EEG data were recorded during both a Performance Alone (PA) condition vs. a Social-Evaluation and Competition (SE&C) condition, which were counterbalanced. Coherence estimates were subjected to a 2 x 2 ANOVA comparing Condition x Hemisphere; post hoc testing was completed using paired-t tests. The arousal-manipulation check of the two experimental protocols (PA vs. SE&C) provided by the autonomic measures and self-reports indicated an increase from a low to moderate level of arousal during the SE&C condition. There was a statistical interaction between condition and hemisphere revealing reduced coherence during SE&C only between T4-Fz (t(14) = 3.084, p = 0.008). Additionally, there was a increase in motor performance (t(13) = 2.171, p = 0.049). Consistent with the inverted-U hypothesis and our predictions as stated for moderate arousal relative to performing alone, there was a subsequent increase in performance coupled with a decrease in coherence between the visuo-spatial and the motor-planning regions. In light of the significantly improved kinematics, the reduction in networking between these task relevant areas is seen as an adaptive refinement of cortico-cortical communication as one moves from low towards optimal arousal.