title: Dynamics of Parkinsonian tremor during deep brain stimulation.
abstract: The mechanism by which chronic, high frequency, electrical deep brain stimulation (HF-DBS) suppresses tremor in Parkinson's disease is unknown. Rest tremor in subjects with Parkinson's disease receiving HF-DBS was recorded continuously throughout switching the deep brain stimulator on (at an effective frequency) and off. These data suggest that the stimulation induces a qualitative change in the dynamics, called a Hopf bifurcation, so that the stable oscillations are destabilized. We hypothesize that the periodic stimulation modifies a parameter affecting the oscillation in a time dependent way and thereby induces a Hopf bifurcation. We explore this hypothesis using a schematic network model of an oscillator interacting with periodic stimulation. The mechanism of time-dependent change of a control parameter in the model captures two aspects of the dynamics observed in the data: (1) a gradual increase in tremor amplitude when the stimulation is switched off and a gradual decrease in tremor amplitude when the stimulation is switched on and (2) a time delay in the onset and offset of the oscillations. This mechanism is consistent with these rest tremor transition data and with the idea that HF-DBS acts via the gradual change of a network property. (c) 2001 American Institute of Physics.
authors.affiliation: Centre for Nonlinear Dynamics in Physiology and Medicine, Physiology Department, McGill University, Montreal, Quebec, Canada H3G 1Y6Centre de Neuroscience de la Cognition, Universite du Quebec a Montreal, Montreal, Quebec, Canada H3C 3P8.
authors.forename: Michele S.
authors.initials: MS
authors.lastname: Titcombe
authors.forename: Leon
authors.initials: L
authors.lastname: Glass
authors.forename: Dominique
authors.initials: D
authors.lastname: Guehl
authors.forename: Anne
authors.initials: A
authors.lastname: Beuter