title: EEG response varies with lesion location in patients with chronic stroke.
abstract: BACKGROUND
  Brain activation differs according to lesion location in functional magnetic resonance imaging (fMRI) studies, but lesion location-dependent electroencephalographic (EEG) alterations are unclear. Because of the increasing use of EEG-based brain-computer-interface rehabilitation, we examined lesion location-dependent EEG patterns in patients with stroke while they performed motor tasks.
  
  
  METHODS
  Twelve patients with chronic stroke were divided into three subgroups according to their lesion locations: supratentorial lesions that included M1 (SM1+), supratentorial lesions that excluded M1 (SM1-), and infratentorial (INF) lesions. Participants performed three motor tasks [active, passive, and motor imagery (MI)] with supination and grasping movements. The hemispheric asymmetric indexes, which were calculated with laterality coefficients (LCs), the temporal changes in the event-related desynchronization (ERD) patterns in the bilateral motor cortex, and the topographical distributions in the 28-channel EEG patterns around the supplementary motor area and bilateral motor cortex of the three participant subgroups were compared with those of the 12 age-matched healthy controls.
  
  
  RESULTS
  The SM1+ group exhibited negative LC values in the active and MI motor tasks, while the other patient subgroups exhibited positive LC values. Negative LC values indicate that the ERD/ERS intensity of the ipsilateral hemisphere is higher than the contralateral hemisphere, whereas positive LC values indicate that the ERD/ERS intensity of the contralateral hemisphere is higher than the ipsilateral hemisphere. The LC values of SM1+ and healthy controls differed significantly (rank-sum test, p < 0.05) in both the supination and grasping movements in the active task. The three patient subgroups differed distinctly from each other in the topography analysis.
  
  
  CONCLUSIONS
  The hemispheric asymmetry and topographic characteristics of the beta band power patterns in the patients with stroke differed according to the location of the lesion, which suggested that EEG analyses of neurorehabilitation should be implemented according to lesion location.
authors.affiliation: Center for Bionics, Korea Institute of Science and Technology, Seoul, 02792, Korea.|Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea.
authors.forename: Wanjoo
authors.initials: W
authors.lastname: Park
authors.affiliation: Graduate School of Technology and Innovation Management, Hanyang University, Seoul, 04763, Korea.
authors.forename: Gyu Hyun
authors.initials: GH
authors.lastname: Kwon
authors.affiliation: Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center Sungkyunkwan University School of Medicine, Seoul, 06351, Korea.|Samsung Advanced Institute for Health Science and Technology, Sungkyunkwan University, Seoul, 06351, Korea.
authors.forename: Yun-Hee
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, Korea. jonghwan_lee@korea.ac.kr.
authors.forename: Jong-Hwan
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Center for Bionics, Korea Institute of Science and Technology, Seoul, 02792, Korea. laehyunk@kist.re.kr.|Department of HCI & Robotics, University of Science and Technology, Daejeon, 34113, Korea. laehyunk@kist.re.kr.
authors.forename: Laehyun
authors.initials: L
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D062207:Brain-Computer Interfaces; D002908:Chronic Disease; D004569:Electroencephalography; D058407:Electroencephalography Phase Synchronization; D005260:Female; D007839:Functional Laterality; D018737:Hand Strength; D006801:Humans; D007092:Imagination; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009068:Movement; D011597:Psychomotor Performance; D020521:Stroke / Q000473:pathology* / Q000503:physiopathology*; D013484:Supination