Corticomuscular communication study by using current source density analysis

Abstract

Corticomuscular communication during wrist motor tasks was investigated in this study. EEG signals from the sensorimotor cortex and EMG data from the reflexive carpi radialis and extensor carpi radialis muscles were recorded from five healthy subjects while performing visual-motor force tasks, with and without perturbation on the wrist. Different continuous perturbation signals with different frequency content (multisines), as well as perturbation resulting in rapid angular displacements of the wrist were applied to study the existence of synchronization on corticomuscular communication, as well as the possible trancortical contribution to the late reflexes on the muscle. Corticomuscular, perturbation- EEG and perturbation - EMG coherences were calculated for all tasks. Three out of five subjects did show high coherence results in beta band when applying multisine perturbation and decreased in base task and in tasks with rapid angular displacements of the wrist, implying an Ia afferent contribution from muscle spindles to beta EEG. The connection of the perturbation to the brain and the muscles is considered non-linear due to high corticomuscular coherence found in harmonics of the excited frequencies. Current source density was applied on frequencies with high corticomuscular coherence. Contralateral supplementary motor cortex is more likely to cause corticomuscular communication at high frequencies of the beta band. Moreover, proprioceptive-evoked potentials were calculated from tasks with continuous rapid angular displacements of the wrist. The basal ganglia is more likely to be involved in the generation of early proprioceptive-evoked activity.