title: Neurophysiological, behavioural and perceptual differences between wrist flexion and extension related to sensorimotor monitoring as shown by corticomuscular coherence.
abstract: OBJECTIVE
  To investigate the effects of neurophysiological, behavioural and perceptual differences between wrist flexion and extension movements, on their corticomuscular coherence (CMC) levels.
  
  
  METHODS
  CMC was calculated between simultaneously recorded electroencephalography (EEG) and electromyography (EMG) measures from fifteen healthy subjects who performed 10 repetitions of alternating isometric wrist flexion and extension tasks at 15% of their maximum voluntary contraction (MVC) torque levels. Task precision was calculated from torque recordings. Subjects rated the perceived difficulty levels for both tasks.
  
  
  RESULTS
  Flexors had significantly lower; peak beta CMC, peak frequency, frequency width, normalised EMG beta power, torque fluctuation (<5 Hz and beta band) and perceived difficulty ratings; but higher MVC and precision compared to extensors. EEG alpha and beta powers were non-different between flexion and extension.
  
  
  CONCLUSIONS
  An inverse relationship between CMC and motor precision was found in our inter-muscle study, contrary to the direct relationship found in a prior intra-muscle study. Functional suitability, long term usage adaptation and lower perceived difficulty of wrist flexion may explain the results.
  
  
  CONCLUSIONS
  We extend the CMC literature to include the clinically different, antagonistic wrist flexors and extensors and add to the debate relating CMC and motor precision by positing the confounding effect of perceived difficulty.
authors.affiliation: MRC/UCT Medical Imaging Research Unit, Division of Biomedical Engineering, Department of Human Biology, University of Cape Town, Faculty of Health Sciences, Anzio Rd, Observatory, 7925 Cape Town, South Africa. Nikhil.Divekar@uct.ac.za
authors.forename: Nikhil V
authors.initials: NV
authors.lastname: Divekar
authors.forename: Lester R
authors.initials: LR
authors.lastname: John
mesh_terms: D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology; D001519:Behavior / Q000502:physiology*; D001611:Beta Rhythm / Q000502:physiology; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D004576:Electromyography; D004585:Electrooculography; D055724:Electrophysiological Phenomena; D005542:Forearm / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D010465:Perception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D014953:Wrist / Q000502:physiology*; D055815:Young Adult