• Christiane Reck, Esther Florin, Lars Wojtecki, Stefan Groiss, Jürgen Voges, Volker Sturm, Alfons Schnitzler, and Lars Timmermann.
• Department of Neurology, University Hospital Cologne, Cologne, Germany. christiane.reck@uk-koeln.de
• Clin Neurophysiol. 2009 Aug 1;120(8):1601-9.

ObjectiveUnder rest condition, beta-band (13-30Hz) activity in patients with Parkinson's disease (PD) is prominent in the subthalamic nucleus (STN). However, the beta-band coupling between STN and muscle activity, its distribution and relation to motor symptoms remains unclear.MethodsUsing up to five electrodes, we recorded local field potentials (LFPs) above (zona incerta, ZI) and within the STN at different recording heights in 20 PD patients during isometric contraction. Simultaneously, we registered activity of the contralateral flexor and extensor muscle. We analysed LFP-EMG coherence to estimate coupling in the frequency domain.ResultsCoherence analysis showed beta-associated coupling in the ZI and STN with more significant LFP-EMG coherences in the STN. Coherence varied depending on the localisation of the LFP and muscles. We found significant difference between coherence of the extensor and the flexor muscle to the same LFP (p=0.045).ConclusionsWe demonstrated that coherence between beta-band oscillations and forearm muscles are differentially distributed in the subthalamic region and between the forearm muscles in Parkinson's disease during isometric contraction. However, the significant LFP-EMG coupling did not associate with motor deficits in PD patients.SignificanceThe differential distribution of beta-band activity in the STN highlights the importance of a topographically distinct therapeutic modulation.

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