Striato-pallidal oscillatory connectivity correlates with symptom severity in dystonia patients

Dystonia is a hyperkinetic movement disorder that has been associated with an imbalance towards the direct pathway between striatum and internal pallidum. To date, the neuronal underpinnings of this abnormal basal ganglia pathway activity and its link to dystonic symptoms remain unknown. Here, we report invasive recordings from ten dystonia patients via specific deep brain stimulation electrodes that allow for unique parallel recordings of several basal ganglia structures. This entails the striatum, the external and the internal pallidum, thus covering nuclei of the direct and indirect pathway. We show that all recorded basal ganglia nuclei display activity in the low frequency band (3–12 Hz). In addition to a correlation between dystonic symptom severity and low-frequency activity in the internal pallidum (R = .88, P = .001), we demonstrate that dystonic symptoms correlate specifically with low-frequency coupling between striatum and internal pallidum (R = .75, P = 0.009). These findings point towards a pathophysiological role of the direct striato-pallidal pathway in dystonia that is conveyed via coupling in the enhanced low-frequency band. Our study provides novel mechanistic insight into the pathophysiology of dystonia by revealing a link between symptom severity and frequency-specific coupling of distinct basal ganglia pathways.