Neurophysiological, behavioural and perceptual differences between wrist flexion and extension related to sensorimotor monitoring as shown by corticomuscular coherence.

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. SIGNIFICANCE: 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.