Influence of focal vibration over Achilles tendon on the activation of sensorimotor cortex in healthy subjects and subacute stroke patients

The modulation of cerebral activity could induce plastic changes in the cerebral cortex and contribute to motor rehabilitation. Focal vibration over lower-extremity muscles has therapeutic effects on the impaired motor function for stroke patients, but the modulatory effects of focal vibration on brain activity are less known. To explore this problem, this experiment was designed and conducted, in which focal vibration (75 Hz) was applied over the right Achilles tendon of 14 healthy subjects and the affected Achilles tendon of seven subacute stroke patients. Electroencephalography was recorded in the following phases: resting-state and three focal vibration sessions. Electroencephalographical analysis showed a significantly desynchronized power of contralateral primary sensorimotor cortex (S1-M1) in beta1 band (13-18 Hz) following all focal vibration sessions occurred in healthy subjects compared to resting-state, whereas a significantly desynchronized power of bilateral S1-M1 in the beta1 and beta2 band (18-21 Hz) was observed in stroke patients compared to resting-state. Besides, event-related power desynchronization of bilateral S1-M1 in stroke patients was significantly lower than healthy subjects in the beta2 and beta3 band (21-30 Hz) during focal vibration sessions. These results demonstrated that focal vibration over Achilles tendon could activate bilateral S1-M1 in stroke patients, which was different in healthy subjects. These indications contribute to a better understanding of the underlying mechanism of focal vibration on stroke rehabilitation.