title: Modulation of event-related desynchronization during kinematic and kinetic hand movements.
abstract: BACKGROUND
  Event-related desynchronization/synchronization (ERD/ERS) is a relative power decrease/increase of electroencephalogram (EEG) in a specific frequency band during physical motor execution and mental motor imagery, thus it is widely used for the brain-computer interface (BCI) purpose. However what the ERD really reflects and its frequency band specific role have not been agreed and are under investigation. Understanding the underlying mechanism which causes a significant ERD would be crucial to improve the reliability of the ERD-based BCI. We systematically investigated the relationship between conditions of actual repetitive hand movements and resulting ERD.
  
  
  METHODS
  Eleven healthy young participants were asked to close/open their right hand repetitively at three different speeds (Hold, 1/3 Hz, and 1 Hz) and four distinct motor loads (0, 2, 10, and 15 kgf). In each condition, participants repeated 20 experimental trials, each of which consisted of rest (8-10 s), preparation (1 s) and task (6 s) periods. Under the Hold condition, participants were instructed to keep clenching their hand (i.e., isometric contraction) during the task period. Throughout the experiment, EEG signals were recorded from left and right motor areas for offline data analysis. We obtained time courses of EEG power spectrum to discuss the modulation of mu and beta-ERD/ERS due to the task conditions.
  
  
  RESULTS
  We confirmed salient mu-ERD (8-13 Hz) and slightly weak beta-ERD (14-30 Hz) on both hemispheres during repetitive hand grasping movements. According to a 3 × 4 ANOVA (speed × motor load), both mu and beta-ERD during the task period were significantly weakened under the Hold condition, whereas no significant difference in the kinetics levels and interaction effect was observed.
  
  
  CONCLUSIONS
  This study investigates the effect of changes in kinematics and kinetics on resulting ERD during repetitive hand grasping movements. The experimental results suggest that the strength of ERD may reflect the time differentiation of hand postures in motor planning process or the variation of proprioception resulting from hand movements, rather than the motor command generated in the down stream, which recruits a group of motor neurons.
authors.forename: Kosei
authors.initials: K
authors.lastname: Nakayashiki
authors.forename: Midori
authors.initials: M
authors.lastname: Saeki
authors.forename: Yohei
authors.initials: Y
authors.lastname: Takata
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Hayashi
authors.affiliation: Department of Computer and Information Sciences, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, 184-8588, Tokyo, Japan. t_kondo@cc.tuat.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kondo
mesh_terms: D001696:Biomechanical Phenomena; D062207:Brain-Computer Interfaces; D004569:Electroencephalography; D058407:Electroencephalography Phase Synchronization / Q000502:physiology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006225:Hand / Q000502:physiology; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007092:Imagination / Q000502:physiology; D007700:Kinetics; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D055815:Young Adult