Electrophysiological manifestations of mirror visual feedback during manual movementby Gadi Bartur, Hillel Pratt, Ruth Dickstein, Silvi Frenkel-Toledo, Amir Geva, Nachum Soroker

Brain Research


Molecular Biology / Clinical Neurology / Neuroscience (all) / Developmental Biology


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Florian A. Kagerer, Jose L. Contreras-Vidal



Available online at www.sciencedirect.com

Research Report

Electrophysiological feedback during man

Gadi Bartura,b,n, Hillel Prattc,

Amir Gevad, Nachum Soroker lty of S th Med n—Isra eer-Sh

Univer tion, Lo agnitude of eventthe moving hand. nant hand. In the mirror pointed to when the moving uates hemispheric or neuron system.

Significance: As each of the above two effects reached significance only in one hand

VF might show a . ll rights reserved. b r a i n r e s e a r c h 1 6 0 6 ( 2 0 1 5 ) 1 1 3 – 1 2 4E-mail address: bargad@hotmail.com (G. Bartur).http://dx.doi.org/10.1016/j.brainres.2015.02.029 0006-8993/& 2015 Elsevier B.V. All rights reserved. ☆The study was conducted in the department of neurological rehabilitation, Loewenstein Hospital, Raanana, Israel. nCorresponding author at: Department of Physical Therapy, Faculty of Social Welfare and Health Studies, University of Haifa, Haifa,

Israel.(dominant and non-dominant, respectively), clinical application of M different level of efficacy in the treatment of right and left hemiparesis & 2015 Elsevier B.V. AEEG

Event-related de-synchronization

Mirror visual feedback

Stroke rehabilitation

Inter-hemispheric dynamics

Mirror neuron system

MVF on EEG oscillations was studied in 3 distinct frequency ranges ( low beta).

Results: Analysis of the low beta range showed that MVF reduces the m related de-synchronization (ERD) in the hemisphere contra-lateral to

This effect reached significance when the moving hand was the domi analysis of the low mu range, bi-hemispheric amplification of ERD by the an added effect of neural recruitment. This effect reached significance hand was the non-dominant hand.

Conclusions: MVF applied during unilateral manual movement (a) atten activation asymmetry, and (b) is likely to involve recruitment of the mirrKeywords: repeated unilateral wrist extension movements with and without MVF. The effect of low mu, high mu,Article history:

Accepted 12 February 2015

Available online 23 February 2015a r t i c l e i n f o a b s t r a c taDepartment of Physical Therapy, Facu bDepartment of Physical Therapy, Reu cEvoked Potentials Laboratory, Technio dBen-Gurion University of the Negev, B eSackler Faculty of Medicine, Tel Aviv fDepartment of Neurological Rehabilitamanifestations of mirror visual ual movement$

Ruth Dicksteina, Silvi Frenkel-Toledoe,f, e,f ocial Welfare and Health Studies, University of Haifa, Haifa, Israel ical Center, Tel Aviv, Israel el Institute of Technology, Haifa, Israel eba, Israel sity, Tel Aviv, Israel ewenstein Hospital, Raanana, Israel

Objective: To investigate the neurophysiological manifestations of the mechanism underlying the effects of Mirror Visual Feedback (MVF) during manual movement.

Method: Thirteen healthy right handed individuals were assessed while performing balance during movement preparation and execution (Serrien et al., 2006), could also affect the results. Thus, in the current study we explored the neurophysiological effects of MVF during both preparation and execution of movement, separately for each hand. We analyzed the EEG pattern during repeated unilateral wrist extension movements done with- and without

MVF, in a group of healthy right handed subjects. Quantitative

EEG spectral analysis (Pfurtscheller and Lopes da Silva, 1999), time-locked to EMG activity recorded from the moving hand, served to assess the bilateral hemispheric dynamics during the preparation and execution stages of the movement (Alegre et al., 2003; Cassim et al., 2000; Neuper and Pfurtscheller, 2001; po0.032]. No other significant effects were observed in this 6 0 6 ( 2 0 1 5 ) 1 1 3 – 1 2 41. Introduction

At present, the majority of stroke patients seriously affected in upper limb (UL) function remain with severe motor disability or even a completely non-functional limb, despite all rehabilitation efforts (Gebruers et al., 2010). Consequently, extensive clinical research is dedicated in recent years to find novel rehabilitation means to improve the functional outcome of the hemiparetic UL. Mirror visual feedback (MVF) is one approach that has emerged from these efforts (Altschuler et al., 1999). In its usual application, MVF involves execution of movement in one limb, when a mid-sagittal mirror reflecting the movement makes it appear as occurring in the contralateral limb. It is simple, inexpensive, easy to implement, and has shown promising results in clinical trials addressing stroke-related hemiparesis (Altschuler et al., 1999; Dohle et al., 2009; Yavuzer et al., 2008), as well as phantom limb pain (Chan et al., 2007) and complex regional pain syndrome (McCabe et al., 2003).

Based on a recent literature review of MVF effectiveness, a recommendation has been made for its use as an adjuvant to current stroke therapy (Thieme et al., 2012).

The exact mechanism underlying the beneficial effects of

MVF remains unclear, a fact limiting its optimal use in clinical practice. Ramachandran and Altschuler (2009) originally hypothesized that paralysis following stroke has a learned component evoked by non-use. The mirror, he argues, helps to reverse this effect by exposing the lost motor action to the patient. An effect on inter-hemispheric dynamics is suggested by the fact that observation of the mirror image creates an illusion of bilateral simultaneous movement, a state implying concomitant bi-hemispheric activation (Cauraugh et al., 2010;

Walsh et al., 2008). MVF is likely to facilitate the activation of motor engrams corresponding to the viewed illusory movement, in a way similar to the facilitation induced by motor imagery (Sharma et al., 2006), or by observation of movements done by others, allegedly, through activation of the mirror neuron system, (MNS) (Hari, 2006; Ertelt et al., 2007). It has also been suggested that the image of a normal movement in the paretic hand (as seen by the mirror reflection) may help patients overcome the impairment in motor control induced by deficient proprioception which is often present after stroke (Altschuler et al., 1999). Trans-cranial Magnetic Stimulation (TMS) studies aimed to assess the effect of MVF on the excitability of the motor cortex ipsilateral to the moving hand, showed enhanced excitability (in the right hemisphere) during movement of the right hand (Garry et al., 2005; Nojima et al., 2012; Tominaga et al., 2009). However, this effect was not shown (in the left hemisphere) during activity of the left hand (Funase et al., 2007), unless a combination of MVF and motor imagery was requested (Fukumura et al., 2007). A TMS study that evaluated the effect of repeated MVF training (using righthand movements) found an inhibitory effect on the contralateral (left) M1 coupled with excitation of the ipsilateral (right)