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

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.