Motor Cortex Plasticity during Unilateral Finger Movement with Mirror Visual Feedback.

Hatice Kumru,Daniel Leon,Josep Maria Tormos,Raul Pelayo,Dolor Soler,Sergiu Albu,John Rothwell,Eloy Opisso

doi:10.1155/2016/6087896

Abstract

Plasticity is one of the most important physiological mechanisms underlying motor recovery from brain lesions. Rehabilitation methods, such as mirror visual feedback therapy, which are based on multisensory integration of motor, cognitive, and perceptual processes, are considered effective methods to induce cortical reorganization. The present study investigated 3 different types of visual feedback (direct, mirrored, and blocked visual feedback: DVF, MVF, and BVF, resp.) on M1 cortex excitability and intracortical inhibition/facilitation at rest and during phasic unimanual motor task in 11 healthy individuals. The excitability of the ipsilateral M1 cortex and the intracortical facilitation increased during motor task performance in the DVF and MVF but not in the BVF condition. In addition, MVF induced cortical disinhibition of the ipsilateral hemisphere to the index finger performing the motor task, which was greater when compared to the BVF and restricted to the homologue first dorsal interosseous muscle. The visual feedback is relevant to M1 cortex excitability modulation but the MVF plays a crucial role in promoting changes in intracortical inhibition in comparison to BVF. Altogether, it can be concluded that a combination of motor training with MVF therapy may induce more robust neuroplastic changes through multisensory integration that is relevant to motor rehabilitation.

Highlights

Change of balance in cortical and intracortical excitability is one of the most important neurophysiological mechanisms underlying motor recovery from brain lesions such as a stroke [1]
We evaluated the short intracortical inhibition (SICI) and short intracortical facilitation (SICF) using paired-pulse Transcranial Magnetic Stimulation (TMS) [15] by applying two stimuli: a subthreshold conditioning stimulus (80% of resting motor threshold (RMT)) and a suprathreshold test stimulus (120% of RMT) at interstimulus interval (ISI) of 2 ms for SICI and 10 ms for SICF
Seeing the active hand performing the motor task, either directly (DVF) or in the mirror (MVF), was associated with a statistically significant increase in the MEPs amplitude compared to resting condition in the direct visual feedback (DVF) (p = 0.008, Wilcoxon test) and Mirror visual feedback (MVF) (p = 0.01, Wilcoxon test) but not in the blocked visual feedback (BVF) condition (p = 0.42, Wilcoxon test)

Summary

Introduction

Change of balance in cortical and intracortical excitability is one of the most important neurophysiological mechanisms underlying motor recovery from brain lesions such as a stroke [1]. Methods based on multisensory integration of motor, cognitive, and perceptual processes through action observation, mental training, and virtual reality have been proven to be effective methods to induce more efficient cortical reorganization and to promote functional recovery in stroke patients [3, 4]. Compared to passive movement observation, MVF was associated with enhanced engagement of the M1 cortex controlling the active hand and induced additional activation in the contralateral M1, the supplementary motor area, the supramarginal gyrus, the superior parietal lobe, and the primary and higher-order visual areas involved in solving the perceptual incongruences [10,11,12].

Methods

Results

Conclusion