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Title: Frequency-domain and nonlinear analysis of local field potentials and clinical efficacy of deep brain stimulation for complex tremors
Author: Holland, Peter James
ISNI:       0000 0004 2723 7729
Awarding Body: Oxford University
Current Institution: University of Oxford
Date of Award: 2011
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Recent years have seen increasing interest in the application of ideas and techniques from the field of dynamical systems theory to neurological signals. However, the applicability of these potentially powerful methods to basal ganglia local field potentials is yet to be established. This thesis attempts to prove the merit of employment ofthese methods in the analysis of signals which represent one of the few chances to record subcortical electropbysiological activity in the awake human. Tbe nonlinear analysis technique of Recurrence Quantification Analysis was employed due to its robustness to noise and nonstationarity. The presence of non linear dynamics in local field potentials recorded from the subtbalamic nucleus, globus pallidus and motor thalamus of movement disorders patients is established for the first time using surrogate data testing, validating the suitability of this technique. Indicating its potential capability, Recurrence Quantification Analysis proves effective in discriminating local field potentials recorded from the globus pallidus and the subthalamic nucleus where spectral measures do not. Alterations in linear and nonlinear aspects of subthalamic nucleus local field potentials due to the effects of dopaminergic medication are also demonstrated. Evidence for differences in the pattern of coherence between simultaneously recorded globus pallidus and thalamic local field potentials between dystonic and tremulous patients is provided and related to bivariate nonlinear statistics. The clinical efficacy of Deep Brain Stimulation is investigated in a group of patients suffering from complex tremor resulting from acquired brain injury, with significant postoperative improvement demonstrated. However, the inability of Deep Brain Stimulation to treat ataxia, which is also a common problem in the treatment of tremor associated with multiple sclerosis, is noted in this group. In order to improve multiple sclerosis patient selection a method is developed based on the power spectrum of the electromyogram and shown to correlate significantly with clinical outcome.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available