Kinesiology
Permanent URI for this communityhttp://hdl.handle.net/1903/2253
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Item HIPPOCAMPAL GLUCOSE TRANSPORT AND OXIDATION IN RESPONSE TO DISRUPTED BLOOD FLOW IN AN AGING RAT MODEL OF HEART FAILURE(2023) Pena, Gabriel Santiago; Smith, J. Carson; Kuzmiak-Glancy, Sarah; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The primary objective of this dissertation was to investigate, in a rodent model of cardiovascular disease promoted by transverse aortic constriction (TAC), whether cerebral hypoperfusion stemming from chronic high pulsatile blood flow, and cerebral hypoperfusion stemming from low cerebral blood flow differentially affected hippocampal glucose transport and hippocampal mitochondrial function. We first, characterized the changes in right and left carotid hemodynamics and diameter in response to TAC and in a SHAM control group at three different time points (20-, 30-, and 40 weeks) post-surgery. Then, right, and left hippocampal mitochondrial content and substrate oxidation were investigated, and protein expression of glucose transporters and mitochondrial quality control markers were quantified. In this study, both the SHAM and TAC conditions included male and female rats to address possible sex differences. We report that all time points within TAC, right carotid blood flow velocities and pulsatility were greater than the left, but did not worsen over time. No differences in mitochondrial content were found within TAC nor between TAC and SHAM, but within TAC animals there were impairments in right hippocampal coupled and uncoupled respiration when compared to the left. When compared to the SHAM controls, right and left hippocampi of TAC animals had higher protein expression of mitochondrial quality control markers, but no differences in glucose transporter expression were found. Thus, while both high blood flow and/or pulsatility as well as low cerebral blood flow may lead to brain hypoperfusion, the metabolic consequences of the two may not be the same. The results from this dissertation contribute to the expanding literature characterizing the intersection between cardiovascular disease and neurodegeneration.Item 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.Item CARDIORESPIRATORY FITNESS AND BASAL FOREBRAIN CHOLINERGIC NETWORKS IN OLDER ADULTS(2021) Won, Junyeon; Smith, J. Carson; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)BACKGROUND: Age-related cholinergic dysfunction within the basal forebrain (BF) is associated with cognitive decline and Alzheimer’s disease (AD) in older adults. Accumulating evidence suggests that higher cardiorespiratory fitness (CRF) is linked to neuroprotective effects. However, we have yet to understand the associations between CRF, BF cholinergic function, and cognitive function in older adults. In humans, resting state functional connectivity (rsFC) using functional MRI (fMRI) is useful to characterize the functional aspect of the BF cholinergic connectivity. PURPOSE: 1) To investigate the relationships between CRF-BF rsFC, CRF-cognitive performance, and BF rsFC-cognitive performance in older adults; 2) To investigate the moderating effects of CRF in the relationship between BF rsFC and cognitive function; 3) To investigate the possibility of BF rsFC as a neurophysiological mechanism underpinning the association between CRF and cognitive function in older adults. METHODS: We utilized a publicly available dataset from the Nathan Kline Institute Rockland Sample in which CRF, cognitive test scores (e.g., Rey Auditory Verbal Learning Test, Delis-Kaplan color-word Interference test, and D Delis-Kaplan trail making test), and fMRI data are available in a large sample of older adults. Resting-state fMRI were preprocessed using a rigorous method and valid image processing software. Linear regression models were used to assess the associations between CRF, BF rsFC, and cognitive performance in Specific Aim 1. Sex-dependent differences in the BF rsFC were also investigated as a post-hoc analysis. The interaction between CRF and BF rsFC on cognitive performance was tested using linear regression and analysis of covariance (ANCOVA) for Specific Aim 2. Mediation analysis was administered to examine the possible mediating role of BF rsFC in the relationship between CRF and cognitive function (Specific Aim 3). RESULTS: There was an association between higher CRF and greater NBM rsFC in older adults. There were significant correlations between CRF, CRF-related NBM rsFC, and trail making test performance only in women. Importantly, higher CRF was associated with better Trail Making performance through greater NBM rsFC in females. Lastly, higher CRF was associated with a greater positive association between NBM rsFC and Color-Word Interference performance in older women. CONCLUSION: Higher CRF is associated with greater NBM rsFC in older adults. The association between higher CRF and better executive function performance, however, was evident only in females. Our results further provide evidence that the NBM rsFC may be an underlying neural mechanism in the relationship between CRF and executive function specifically in older women. Hence, sex differences may exist within the CRF-related neuroprotective effects on the NBM functional network and executive function.Item Cerebral Cortical Networking for Mental Workload Assessment during Practice of a Novel Motor Skill(2021) Galway, William; Gentili, Rodolphe; Kinesiology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Although many studies have investigated mental workload during performance, its examination through functional connectivity during motor practice/learning is limited thus requiring further investigations. Therefore, this work aims to examine performance and functional connectivity dynamics underlying mental workload during motor practice by combining a robust computational method to derive connectivity and a human-machine interface which mitigates the use of participants’ prior motor experience since it can bias the acquisition process. Participants practiced reaching with a robotic arm through a head-controlled interface while kinematics and EEG were collected. The robotic end-effector kinematics quantified the performance and the Weighted Phase Lag Index indexed the connectivity during movement planning. Although performance improved during practice, the functional connectivity dynamics suggest that the recruitment of cognitive- motor resources decreased to a certain extent but that further training is likely needed to attenuate the mental workload. The work can also inform the training and design of assistive devices.