Modulation of Corticomuscular Coupling With Split-Belt Locomotor Adaptation in Healthy Young Males

Humans can adjust their walking patterns in response to both internal and external demands, a process referred to as locomotor adaptation. This process is crucial for walking in complex environments and is thought to be driven by sensory prediction errors. While the involvement of supraspinal structures is known, how the oscillatory coupling between the sensorimotor cortex and spinal motor neurons is involved in locomotor adaptation remains unclear. This study aimed to characterize the modulation of corticomuscular coherence (CMC), an index of this coupling, using a split-belt locomotor adaptation paradigm. We recorded electroencephalogram (EEG) and electromyogram (EMG) from the tibialis anterior muscle and calculated CMC in the alpha (8-12 Hz) and beta (12-32 Hz) bands. Results revealed that immediately following the application and removal of the perturbation, both alpha and beta CMC temporarily decreased compared to normal walking, suggesting a disruption of established corticomuscular coupling. However, during the adaptation process, alpha CMC in the slow leg's heel contact phase significantly increased toward normal walking levels. During de-adaptation, both alpha and beta CMC increased, and finally, CMC in all gait phases returned to normal walking levels. These results suggest that corticomuscular coupling was enhanced during the adaptation and de-adaptation processes. Thus, modulation of corticomuscular coupling may be associated with the adjustment of gait patterns to meet environmental demands. These findings will advance our understanding of neuromuscular control of gait and offer valuable insights for gait rehabilitation.