Computational and Mathematical Methods in Medicine
Volume 8 (2007), Issue 3, Pages 165-171
doi:10.1080/17486700701502363
Original Article

Evidence of Intermittency in the Local Field Potentials Recorded from Patients with Parkinson's Disease: A Wavelet-Based Approach

Asok K. Sen1 and Jonathan O. Dostrovsky2

1Department of Mathematical Sciences, Indiana University, 402 N. Blackford Street, Indianapolis, IN 46202, USA
2Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada

Received 15 January 2007; Revised 24 May 2007; Accepted 8 June 2007

Copyright © 2007 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Using a continuous wavelet transform we have detected the presence of intermittency in the beta oscillations of the local field potentials (LFPs) that were recorded from the subthalamic nucleus (STN) of patients with Parkinson's disease. The intermittent behavior was identified by plotting the wavelet power spectrum of the LFP signal on a time–frequency plane. We also computed the temporal variations of scale-averaged wavelet power and wavelet entropy (WE). An intermittent pattern is characterized by large amounts of power over very short periods of time separated by almost quiescent periods. Time-localized changes in WE further support the evidence of intermittency. The cause and significance of the intermittent beta activity are presently unclear. It may be due to complex interactions of the cortico-basal-ganglia networks converging at the STN level.