Prolonged local vibration (LV) is thought to promote brain plasticity through repeated Ia afferents discharge. However, the underlying mechanisms remain unclear. This study therefore aimed at determining the acute after-effects of 30-min LV of the flexor carpi radialis muscle (FCR) on sensorimotor (S1, M1) and posterior parietal cortex (PPC) areas activity. Sixteen healthy participants were tested before and immediately after 30 min of FCR LV. Electroencephalographic signals were recorded during isometric submaximal wrist flexions. Time-frequency analyses were performed at source levels during contraction preparation, contraction initiation, force plateau and relaxation. After LV, the results showed an increase in alpha and beta desynchronizations in the source activity for the estimated M1, S1 and PPC during contraction preparation (p ≤ 0.05) and contraction initiation (p ≤ 0.05; except for PPC in the beta band: p = 0.07), as well as a greater alpha desynchronization in M1, S1 and PPC (p < .01) during force plateau. No LV-induced changes were observed during relaxation. Prolonged LV on the upper limb could increase estimated cortical activity within M1, S1 and PPC areas during subsequent isometric contractions. This could be due to LV-induced Ia afferents inputs projecting onto cortical areas through proprioceptive pathways, and likely triggering brain use-dependent plasticity.
Keywords: EEG; M1; PPC; S1; local vibration.