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Upper extremity rehabilitation of stroke: Facilitation of corticospinal excitability using virtual mirror paradigm

Youn Joo Kang12, Hae Kyung Park1, Hyun Jung Kim1, Taeo Lim1, Jeonghun Ku3*, Sangwoo Cho4, Sun I Kim45 and Eun Sook Park2

Author Affiliations

1 Department of Rehabilitation Medicine, Eulji Hospital, Eulji University School of Medicine Seoul, Seoul, Korea

2 Department of Physical Medicine and Rehabilitation, Graduate School, Yonsei University, Seoul, Korea

3 Department of Biomedical Engineering, Keimyung University, Daegu, Korea

4 Department of Biomedical Engineering, Hanyang University, Seoul, Korea

5 Medical Device Development Center, Osong Medical Innovation Foundation, Chungbuk, Korea

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Journal of NeuroEngineering and Rehabilitation 2012, 9:71  doi:10.1186/1743-0003-9-71

Published: 4 October 2012



Several experimental studies in stroke patients suggest that mirror therapy and various virtual reality programs facilitate motor rehabilitation. However, the underlying mechanisms for these therapeutic effects have not been previously described.


We attempted to delineate the changes in corticospinal excitability when individuals were asked to exercise their upper extremity using a real mirror and virtual mirror. Moreover, we attempted to delineate the role of visual modulation within the virtual environment that affected corticospinal excitability in healthy subjects and stroke patients.


A total of 18 healthy subjects and 18 hemiplegic patients were enrolled into the study. Motor evoked potential (MEP)s from transcranial magnetic stimulation were recorded in the flexor carpi radialis of the non-dominant or affected upper extremity using three different conditions: (A) relaxation; (B) real mirror; and (C) virtual mirror. Moreover, we compared the MEPs from the virtual mirror paradigm using continuous visual feedback or intermittent visual feedback.


The rates of amplitude increment and latency decrement of MEPs in both groups were higher during the virtual mirror task than during the real mirror. In healthy subjects and stroke patients, the virtual mirror task with intermittent visual feedback significantly facilitated corticospinal excitability of MEPs compared with continuous visual feedback.


Corticospinal excitability was facilitated to a greater extent in the virtual mirror paradigm than in the real mirror and in intermittent visual feedback than in the continuous visual feedback, in both groups. This provides neurophysiological evidence supporting the application of the virtual mirror paradigm using various visual modulation technologies to upper extremity rehabilitation in stroke patients.

Stroke; Corticospinal excitability; Transcranial magnetic stimulation; Virtual reality; Feedback