Facilitating motor imagery practice with synchronous action observation for stroke patients

It is known that Motor Imagery (MI) improves neurorehabilitation in stroke patients while action observation (AO) has the potential to facilitate MI. However, little is known about how to use AO effectively in MI practice. The aim of our study is to compare the effectiveness of synchronous and asynchronous AO in facilitating MI for neurorehabilitation of stroke patients. The participants with hand motor dysfunction following stroke were asked to imagine a specific object insertion and removal task guided by synchronous or asynchronous AO during MI practice. The event-related power decrease (ERD) or event-related power increase (ERS) in sensorimotor rhythms (SMR) of electroencephalographic (EEG) was calculated to evaluate the cortex excitation during MI. The Nine Hole Peg Test (NHPT) and Pinch Strength Test (PST) were used to score functional recovery of the paralyzed hand. The effectiveness of MI was evaluated according to the cortex excitation and the scores of hand functional recovery. The results of ERD in EEG SMR indicate that synchronous AO increases cortex excitation more effectively than asynchronous AO in MI. Meanwhile, higher NHPT and PST scores were achieved after MI training guided by synchronous AO. This reflects that the hand motor function is also improved more significantly by MI practice guided by synchronous AO. Therefore, compared to asynchronous AO, synchronous AO significantly facilitates MI practice and leads to more effective neurorehabilitation of stroke patients.