title: Parkinson subtype-specific Granger-causal coupling and coherence frequency in the subthalamic area.
abstract: Previous work on Parkinson's disease (PD) has indicated a predominantly afferent coupling between affected arm muscle activity and electrophysiological activity within the subthalamic nucleus (STN). So far, no information is available indicating which frequency components drive the afferent information flow in PD patients. Non-directional coupling e.g. by measuring coherence is primarily established in the beta band as well as at tremor frequency. Based on previous evidence it is likely that different subtypes of the disease are associated with different connectivity patterns. Therefore, we determined coherence and causality between local field potentials (LFPs) in the STN and surface electromyograms (EMGs) from the contralateral arm in 18 akinetic-rigid (AR) PD patients and 8 tremor-dominant (TD) PD patients. During the intraoperative recording, patients were asked to lift their forearm contralateral to the recording side. Significantly more afferent connections were detected for the TD patients for tremor-periods and non-tremor-periods combined as well as for only tremor periods. Within the STN 74% and 63% of the afferent connections are associated with coherence from 4-8Hz and 8-12Hz, respectively. However, when considering only tremor-periods significantly more afferent than efferent connections were associated with coherence from 12 to 20Hz across all recording heights. No difference between efferent and afferent connections is seen in the frequency range from 4 to 12Hz for all recording heights. For the AR patients, no significant difference in afferent and efferent connections within the STN was found for the different frequency bands. Still, for the AR patients dorsal of the STN significantly more afferent than efferent connections were associated with coherence in the frequency range from 12 to 16Hz. These results provide further evidence for the differential pathological oscillations and pathways present in AR and TD Parkinson patients.
authors.affiliation: Department of Neurology, University Hospital Cologne, Kerpener Strasse 62, 50937 Köln, Germany; Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine University Düsseldorf, Germany. Electronic address: Esther.Florin@hhu.de.
authors.forename: Esther
authors.initials: E
authors.lastname: Florin
authors.affiliation: Department of Economics, University of Mannheim, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Pfeifer
authors.affiliation: Department of Stereotaxy and Functional Neurosurgery, University Hospital of Cologne, Germany.
authors.forename: Veerle
authors.initials: V
authors.lastname: Visser-Vandewalle
authors.affiliation: Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine University Düsseldorf, Germany.
authors.forename: Alfons
authors.initials: A
authors.lastname: Schnitzler
authors.affiliation: Department of Neurology, University Hospital Cologne, Kerpener Strasse 62, 50937 Köln, Germany. Electronic address: Lars.Timmermann@uk-koeln.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Timmermann
mesh_terms: D000328:Adult; D000368:Aged; D001132:Arm / Q000503:physiopathology*; D046690:Deep Brain Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D064795:Intraoperative Neurophysiological Monitoring; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009043:Motor Activity / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010300:Parkinson Disease / Q000503:physiopathology* / Q000601:surgery / Q000628:therapy; D012815:Signal Processing, Computer-Assisted; D020531:Subthalamic Nucleus / Q000503:physiopathology* / Q000601:surgery
keywords: coherence; connectivity; deep brain stimulation; directionality; human; subthalamic nucleus