Abstract
The neural control of muscular activity during a voluntary movement implies a continuous updating of a mix of afferent and efferent information. Corticomuscular coherence (CMC) is a powerful tool to explore the interactions between the motor cortex and the muscles involved in movement realization. The comparison of the temporal dynamics of CMC between healthy subjects and post-stroke patients could provide new insights into the question of how agonist and antagonist muscles are controlled related to motor performance during active voluntary movements. We recorded scalp electroencephalography activity, electromyography signals from agonist and antagonist muscles, and upper limb kinematics in eight healthy subjects and seventeen chronic post-stroke patients during twenty repeated voluntary elbow extensions and explored whether the modulation of the temporal dynamics of CMC could contribute to motor function impairment. Concomitantly with the alteration of elbow extension kinematics in post-stroke patients, dynamic CMC analysis showed a continuous CMC in both agonist and antagonist muscles during movement and highlighted that instantaneous CMC in antagonist muscles was higher for post-stroke patients compared to controls during the acceleration phase of elbow extension movement. In relation to motor control theories, our findings suggest that CMC could be involved in the online control of voluntary movement through the continuous integration of sensorimotor information. Moreover, specific alterations of CMC in antagonist muscles could reflect central command alterations of the selectivity in post-stroke patients.
Highlights
Understanding how agonist and antagonist muscles activity is controlled during goal-directed and precise movements is an ongoing challenge in understanding neural control of human movement
corticomuscular coherence (CMC) can be taken as a descriptor of the brain-muscle functional connectivity, defined as a measure of the functional coupling between sensorimotor cortex and muscular activity obtained from electroencephalography (EEG) and electromyography (EMG) during muscular contraction (Conway et al, 1995; Halliday et al, 1998; Mima and Hallett, 1999; Salenius and Hari, 2003; Baker, 2007)
For the same functional task of elbow extension performed by both healthy controls and post-stroke patients, the analysis revealed between-groups differences in motor performance
Summary
Understanding how agonist and antagonist muscles activity is controlled during goal-directed and precise movements is an ongoing challenge in understanding neural control of human movement. Movement control implies continuous integration of afferent and efferent information (Campfens et al, 2013) during both preparatory and online control phases of movement execution (Buneo and Andersen, 2006) This argues for the involvement of continuous communication between the brain and muscles to drive efficiently the activity of both agonist and antagonist muscles activated during the movement. Even if it still remains to clearly understand the functional role of such a synchronization between the brain and muscle oscillatory signals (Bourguignon et al, 2019), most studies on CMC in motor control endorse the consensus that CMC takes part in the regulation of agonist and antagonist muscles activity (Cremoux et al, 2017; Dal Maso et al, 2017), and is related to sensorimotor integration (Baker, 2007; Witham et al, 2011). CMC is thought to reflect a direct regulation process occurring in the motor system via the corticospinal pathway (Conway et al, 1995; Kristeva et al, 2007)
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