Frequency-dependent distribution of local field potential activity within the subthalamic nucleus in Parkinson's disease.

Enhanced oscillatory local field potential (LFP) activities over a broad frequency range (5-30 Hz) have been consistently reported from the basal ganglia in patients with Parkinson's disease (PD) and in animal models of this disease. Here we test the hypothesis that these activities may have different functional connotations according to their frequency, by seeking a relatively differentiated distribution within the different functional territories of the subthalamic nucleus (STN). To this end we made intra-operative microelectrode recordings of LFP activities within the STN of 8 PD patients undergoing functional neurosurgery. A significantly larger beta (13-30 Hz) power was found in the dorsolateral part of STN, which is related to motor cortical areas, compared to the ventral (associative/limbic) part of STN. This specific topography was not observed for low frequency activity (5-12 Hz). Our data suggest that the relative distribution of oscillatory activity within the STN of patients with PD may differ according to frequency and confirm previously reported findings that beta activity may provide a functional marker for the 'motor' STN in functional neurosurgery.