title: Cortico-muscular coherence in advanced Parkinson's disease with deep brain stimulation.
abstract: OBJECTIVE
  Cortico-muscular coherence (CMC) is thought to reflect the interplay between cortex and muscle in motor coordination. In Parkinson's disease (PD) patients, levodopa has been shown to enhance CMC. This study examined whether subthalamic nucleus (STN) deep brain stimulation (DBS) affects the CMC in advanced PD.
  
  
  METHODS
  Magnetoencephalography (MEG) and electromyography (EMG) measurements were done simultaneously both with DBS on and off to determine the CMC during wrist extension. The spatiotemporal signal space separation (tSSS) was used for artifact suppression.
  
  
  RESULTS
  CMC peaks between 13 and 25 Hz were found in 15 out of 19 patients. The effect of DBS on CMC was variable. Moreover, the correlation between CMC and motor performance was inconsistent; stronger CMC did not necessarily indicate better function albeit tremor and rigidity may diminish the CMC. Patients having CMC between 13 and 25 Hz had the best motor scores at the group level.
  
  
  CONCLUSIONS
  DBS modifies the CMC in advanced PD with large interindividual variability.
  
  
  CONCLUSIONS
  DBS does not systematically modify CMC amplitude in advanced PD. The results suggest that some components of the CMC may be related to the therapeutic effects of DBS.
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, Helsinki University Central Hospital, Finland; Department of Neurology, Helsinki University Central Hospital, Finland. Electronic address: katja.airaksinen@helsinki.fi.
authors.forename: Katja
authors.initials: K
authors.lastname: Airaksinen
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.
authors.forename: Jyrki P
authors.initials: JP
authors.lastname: Mäkelä
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Nurminen
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Luoma
authors.affiliation: Elekta Oy, Helsinki, Finland.
authors.forename: Samu
authors.initials: S
authors.lastname: Taulu
authors.affiliation: Elekta Oy, Helsinki, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Ahonen
authors.affiliation: Department of Neurology, Helsinki University Central Hospital, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Pekkonen
mesh_terms: D000368:Aged; D002540:Cerebral Cortex / Q000503:physiopathology*; D046690:Deep Brain Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008875:Middle Aged; D009127:Muscle Rigidity / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010300:Parkinson Disease / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D020531:Subthalamic Nucleus / Q000503:physiopathology; D014202:Tremor / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy
chemical_list: D007980:Levodopa
keywords: Cortico-muscular coherence; Deep brain stimulation; Magnetoencephalography; Parkinson disease; Rigidity; Subthalamic nucleus