Mirror Visual Feedback Impact on Abductor Pollicis Brevis Muscle Electrical Activity in the Stroke Affected Arm

Abstract

Research background and hypothesis. Stroke is recognized as one of the major causes of morbidity, mortality
and long-term disability around the world (Laver et al., 2012). Mirror visual feedback is one of the newest areas of
research that shows the potential application in neurorehabilitation (Kang et al., 2012). We hypothesize that abductor
pollicis brevis muscle activity in the stroke affected arm will be higher when the movements are performed with
non-affected hand visual mirror feedback.
Research aim was to identify mirror visual feedback impact on abductor pollicis brevis muscle electrical activity
in the stroke affected arm.
Research methods. Post-stroke subjects (n = 12) performed bimanual thumb opposition under three conditions:
without mirror visual feedback, with non-affected and affected arm reflection in the mirror. Electrical activity of
abductor pollicis brevis muscle was recorded simultaniously.
Research results. There was a significantly higher (p < 0.05) muscle activity amplitude when thumb opposition
was performed with visual feedback of non-affected hand compared to task without mirror visual feedback. No
muscle activity amplitude difference was observed when thumb opposition was performed looking at affected hand
mirror visual feedback compared to task without mirror visual feedback. Motor unit firing rate did not differ between
tasks.
Discussion  and  conclusions.  I.  Nojima  and  co-authors  (2012)  have  identified  that  mirror  visual  feedback
activates motor cortex. Additionally, our study shows that even during one-time movement with observation of non-
affected hand in the mirror shows higher muscle electrical activity in the affected hand.

Keywords: mirror neurones, thumb opposition, bimanual movement.