Functional and clinical relevance of oscillatory activity within cortico-basal-ganglia circuits in Parkinson's disease

• Main Author: Oswal, Ashwini
• Other Authors: Brown, Peter ; Litvak, Vladimir
• Published: University of Oxford 2015
• Subjects: 616.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.712488

Over the past 20 years there have been significant advances in our understanding of how synchronised neural oscillations relate to cognitive and motor processes both in health and in neurological disease. Oscillations can be considered from the point of view of being the observations of the latent dynamical properties of interacting populations of neurones. With this in mind it becomes evident that their study may inform about underlying functional architectures and principles governing motor and cognitive control. Cortico-basal-ganglia circuits are canonical feedback loops between cortical and sub-cortical structures, with well-defined anatomy which makes them ideal for the study of oscillatory phenomena. Moreover, these circuits are known to play crucial roles in motor and cognitive processes such that impairments of their normative function may lead to neurological disease states. In this thesis I focus on insights about oscillatory function from cortical-basal ganglia recordings in Parkinson's disease. I will present evidence from studies showing that the roles of beta (15-30 Hz) and gamma (60-90 Hz) oscillatory activities in motor control are intricately linked to task specific cognitive-motor demands. Furthermore, the timing of activities within these frequency bands relative to movement reveals how distinct spectral phenomena may relate to distinct aspects of cognitive and motor processing. An intricately related aim of this thesis is to begin to establish how the preferred frequencies of interaction and the topographies of long range oscillatory networks within cortico-basal-ganglia loops relate to specific clinical symptoms. In this regard, I will present data revealing the modulation of cortico-basal ganglia coupling by movement, and Parkinson's disease therapies such as levodopa and Deep Brain Simulation (DBS). Novel methodological developments that facilitate such insights are presented. Finally I discuss how these insights contribute to existing understanding of the pathophysiology of Parkinson's disease, in addition to suggesting novel future therapeutic strategies for DBS.