Abstract
OBJECTIVE: Dopaminergic treatment of patients with Parkinson's disease can be associated with a finely tuned high-gamma (FTG) band oscillation between 60 and 90 Hz in the basal ganglia (BG) nuclei. This activity, together with suppression of excessive neural synchrony in the beta frequency band (15-30 Hz), is hypothesized to contribute to the pro-kinetic effects of dopaminergic medication. Beta activity, which high-gamma replaces, has been shown to be bilaterally coherent, but whether sub-cortical FTG activity is in some way linked across hemispheres remains unknown. METHODS: We analyse bilateral local field potential activity recorded from the subthalamic nuclei of 10 patients on dopaminergic medication while at rest, following surgery for deep brain stimulation. RESULTS: In three of these patients FTG activities were coherent across the hemispheres. Short duration (≤18 s) bilateral amplitude and frequency co-modulation were recorded in all subjects, although the two phenomena were independent in time and independent of similar episodes in other frequency bands. CONCLUSIONS: FTG co-modulation can be independent of movement and of co-modulation episodes at other frequencies. SIGNIFICANCE: Relatively independent organisation of processing through amplitude and frequency modulation within different frequency bands potentially affords opportunities for functional segregation and multiplexing of processing streams within the BG.