title: Characterisation of tremor-associated local field potentials in the subthalamic nucleus in Parkinson's disease.
abstract: We simultaneously recorded local field potentials (LFPs) in the subthalamic nucleus (STN) and surface electromyographic signals (EMGs) from the extensor and flexor muscles of the contralateral forearm in eight patients with idiopathic tremor-dominant Parkinson's disease (resting tremor) during the bilateral implantation of deep brain stimulation electrodes. Recordings were made at different heights (in 0.5- to 2.0-mm steps beginning outside the STN) using up to five concentrically configured macroelectrodes (2 mm apart). The patients were instructed to relax their contralateral forearm (rest condition). We analysed the coherence between tremor EMGs and STN LFPs, which showed significant tremor-associated coupling at single tremor and double tremor frequencies. Moreover, the EMG-LFP coherences were characterised by differences between antagonistic muscles (flexor, extensor) and by the spatial distribution of LFPs within the STN. Coherence at single and double tremor frequencies occurred significantly more frequently within STN than above STN (in the zona incerta). In this study, we were able to show that, within STN, tremor-associated LFP activity varied with spatial distribution and with the contralateral antagonistic forearm muscles. These findings suggest the existence of distribution- and muscle-specific tremor-associated LFP activity at different tremor frequencies and an organisation of tremor-related subloops within the STN.
authors.affiliation: Department of Neurology, Heinrich-Heine-University, Düsseldorf, Germany. christiane.reck@uk-koeln.de
authors.forename: Christiane
authors.initials: C
authors.lastname: Reck
authors.forename: Esther
authors.initials: E
authors.lastname: Florin
authors.forename: Lars
authors.initials: L
authors.lastname: Wojtecki
authors.forename: Holger
authors.initials: H
authors.lastname: Krause
authors.forename: Stefan
authors.initials: S
authors.lastname: Groiss
authors.forename: Jürgen
authors.initials: J
authors.lastname: Voges
authors.forename: Mohammad
authors.initials: M
authors.lastname: Maarouf
authors.forename: Volker
authors.initials: V
authors.lastname: Sturm
authors.forename: Alfons
authors.initials: A
authors.lastname: Schnitzler
authors.forename: Lars
authors.initials: L
authors.lastname: Timmermann
mesh_terms: D000368:Aged; D001931:Brain Mapping; D004568:Electrodiagnosis / Q000379:methods*; D004576:Electromyography; D004594:Electrophysiology; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D005542:Forearm / Q000294:innervation / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009434:Neural Pathways / Q000033:anatomy & histology / Q000503:physiopathology; D010300:Parkinson Disease / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D020531:Subthalamic Nucleus / Q000033:anatomy & histology / Q000503:physiopathology*; D014202:Tremor / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy