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Locomotor Control In Parkinson Disease
Date of Award
Doctor of Philosophy (PhD)
Parkinson disease (PD) is a common neurodegenerative condition characterized by loss of dopaminergic neurons in the substantia nigra pars compacta. PD produces profound motor impairments including deficits in balance and gait. Locomotion is particularly impaired in PD during challenging locomotor tasks, including turning. Imbalance during gait and turning may lead to falls and serious injury. Various treatment options are available to address deficits in PD, such as pharmacological therapy, surgical interventions, and physical activity-based strategies. We assessed dopaminergic system involvement in deficits in challenging gait tasks and balance in PD by determining if more complex tasks are affected differently than simpler tasks by anti-parkinson medications. Medication improved balance and similarly improved all gait tasks, but deficits remained in all measures compared to controls. Further, we determined if dopaminergic systems contribute to turning deficits in PD by assessing if anti-parkinson medication alters turning. Turning improved partially with medication, but deficits remained, compared to controls. Locomotor deficits remained in people with PD, even during peak efficacy of dopaminergic therapy, suggesting possible involvement of other neurotransmitter systems in these deficits.
Addressing remaining locomotor deficits through other means may reduce fall risk in PD. We determined whether rotating treadmill training provides external cues to reinforce appropriate motor patterns for turning, thereby improving turning in people with PD ON medication. Turning did not improve after rotating treadmill training in people with PD, indicating a need to develop alternative therapeutic strategies. We also examined the effects of deep brain stimulation of the subthalamic nucleus (STN-DBS) on locomotion. Locomotor benefits with STN-DBS are variable, and position of the active contact within the STN may contribute to this variability. We examined STN organization and the potential mechanisms of the effects of STN-DBS by determining whether gait and balance task performance was affected differently by dorsal versus ventral STN-DBS in people with PD. Motor symptoms and gait parameters were similarly improved with dorsal and ventral STN-DBS, suggesting diffuse distribution of relevant connections within the STN. Integrative treatment approaches applying pharmacological, surgical, and physical-activity based interventions may be optimal for addressing locomotor control deficits in people with PD.
Chair and Committee
Gammon M Earhart
Tamara Hershey, Brian T. Edelson, Joel Perlmutter, Paul Stein, Catherine Lang, Daniel Moran
McNeely, Marie E., "Locomotor Control In Parkinson Disease" (2012). Arts & Sciences Electronic Theses and Dissertations. 137.