Event-related desynchronization by hand motor imagery is associated with corticospinal excitability: Physiological evidence for BCI based neurorehabilitation

Abstract

The purpose of this study was to assess the association between the magnitude of event-related desynchronization (ERD) of electroencephalogram, which is believed to represent increased activation of the sensorimotor cortex, and the excitability of primary motor cortex (M1) and spinal motoneurons. M1 excitability was tested by motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) using transcranial magnetic stimulation, and spinal motoneuronal excitability was tested by F-waves using peripheral nerve stimulation. Results showed that MEP amplitude was significantly increased during motor imagery and large ERD during motor imagery was associated with significantly reduced SICI and increased F-wave persistence, but no significant changes in ICF and the response average of F-wave amplitudes. Our findings suggest that ERD magnitude during motor imagery reflects the instantaneous excitability of both M1 and spinal motoneurons.