Frequency dependent effects of subthalamic nucleus stimulation in Parkinson's disease

Excessive synchronisation of basal ganglia activity at frequencies < 30 Hz is a hallmark of the parkinsonian state, and may contribute to bradykinesia. Accordingly, we electrically stimulated chronically implanted subthalamic macroelectrodes in 10 Parkin son's disease patients, after overnight withdrawal of anti-parkinsonian medication. We coin pared the effects of stimulation at 0, 5, 10, 15, 20,25, 30, and ca. 130 Hz by measuring kinesia time (KT) in a tapping task. Although the effects of direct stimulation were small, frequency-response curves demonstrated local peaks at 5-10 Hz and at 20-25 Hz, superimposed upon an overall tendency for KT to reduce with increasing stimulation frequency. This is consistent with the hypothesis that spontaneous activities in these bands might promote bradykinesia. (c) 2005 Elsevier Ireland Ltd. All rights reserved.