UBC Theses and Dissertations
Electrophysiological and motoric effects of galvanic vestibular stimulation in normal and Parkinson's disease subjects Kim, Diana Jean-Young
How vestibular input influences dynamical functional brain networks and sensorimotor processing is an unaddressed area of interest. Previous accounts have suggested that noisy galvanic vestibular stimulation is able to not only improve visuospatial processing in stroke patients, but also ameliorates some of the motor symptoms in Parkinson’s disease. However, the mechanisms through which these purported benefits are obtained are currently poorly understood. In Parkinson’s disease, patients suffer from symptoms of bradykinesia, or slowness of movement, as well as tremor, rigidity, postural instability and cognitive impairment. A proposed mechanism for bradykinesia is that in Parkinson’s disease cortical-basal ganglia-thalamocortical networks are “stuck” in a fixed state, resulting in poorly modulated, exaggerated oscillations resonating in the beta range (13-30 Hz). This thesis addresses a number of questions: What is the effect of external vestibular sensory input on widespread, systems-level oscillatory rhythms? When the brain is in a diseased state, as in Parkinson’s disease, can vestibular input modulate the abnormal dynamics of cortical-basal ganglia networks? Furthermore, is noisy galvanic vestibular stimulation consequently able to affect functional networks and information processing in the brain? Specifically, we investigated whether noisy galvanic vestibular stimulation was able to modulate synchrony of EEG oscillations in normal individuals and Parkinson’s disease subjects. Upon identifying significant neuromodulatory effects of noisy galvanic vestibular stimulation across broadband rhythms in the resting-state EEG activity, we speculated that information processing may be similarly affected in task-related networks in Parkinson’s disease. Subsequently, we investigated whether the same noisy vestibular stimulus would be able to improve motor performance in Parkinson’s disease subjects. We found that their dynamics of motor tracking movements were improved in a visuomotor task by stimulation. We speculate that noisy vestibular stimulation is able to reinstate the abnormal dynamics of functional networks in disease conditions. Therefore, this thesis provides a foundation for assessing the potential utility of galvanic vestibular stimulation as a novel, non-invasive, neuromodulatory therapeutic for Parkinson’s disease.
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