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Mirror visual feedback modulates alpha oscillations in digital mirror therapy for stroke patients

Poster No:

1929

Submission Type:

Late-Breaking Abstract Submission

Authors:

Ya-Ting Chen¹, Chia-Hsiung Cheng¹^,2^,3, Yu-Wei Hsieh¹^,4

Institutions:

¹Department of Occupational Therapy and Graduate Institute of Behavioral Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan, ²Department of Psychiatry, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan, ³Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan, ⁴Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan

First Author:

Ya-Ting Chen
Department of Occupational Therapy and Graduate Institute of Behavioral Sciences
College of Medicine, Chang Gung University, Taoyuan, Taiwan

Co-Author(s):

Chia-Hsiung Cheng
Department of Occupational Therapy and Graduate Institute of Behavioral Sciences|Department of Psychiatry, Chang Gung Memorial Hospital at Linkou|Healthy Aging Research Center, Chang Gung University
College of Medicine, Chang Gung University, Taoyuan, Taiwan|Taoyuan, Taiwan|Taoyuan, Taiwan

Yu-Wei Hsieh
Department of Occupational Therapy and Graduate Institute of Behavioral Sciences|Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital at Linkou
College of Medicine, Chang Gung University, Taoyuan, Taiwan|Taoyuan, Taiwan

Late Breaking Reviewer(s):

Sylvain Baillet
Montreal Neurological Institute
Montreal, Quebec

Rosanna Olsen
Rotman Research Institute, Baycrest Academy for Research and Education
Toronto, Ontario

Sofie Valk
Max Planck Institute for Human Cognitive and Brain Sciences
Leipzig, Saxony

Introduction:

Mirror visual feedback (MVF) utilizes the mirrored image of the motion of one hand to produce the illusion of the movement of the other hand. Traditional mirror therapy (MT) uses MVF derived from the movement of the unaffected hand to induce the illusion of the movement of the affected hand for stroke patients, through placing a mirror along the sagittal plane at an individual's midline. This approach has been considered a potential intervention for stroke patients. Since the reflected image of the unaffected hand in the mirror simulates the motor execution of the affected hand, and may therefore recruit the mirror neuron systems (MNS) and motor areas in the affected hemisphere. Recently, digital-based MT uses a computer monitor placed along the coronal plane in front of the patients to present MVF and has been shown to provide advantages over traditional MT. These benefits include more immersive MVF, better perception of limb ownership, and reduced neck discomfort and postural pressure during rehabilitation. However, whether and how MVF in the digital-based MT modulates the neural activation in the affected hemisphere for stroke patients remain unclear. In this study, we investigated the neural mechanisms underlying MVF in digital-based MT for stroke patients using electroencephalography (EEG).

Methods:

We recorded scalp EEG while 14 stroke participants performed an upper extremity motor task with varying types of MVF (unilateral on the affected side vs. bilateral) and manual movement (unilateral on the unaffected side vs. bilateral) (Figure 1). There were four conditions and the order of conditions was counterbalanced across the participants. In the bilateral manual training (BT) condition, the participants were instructed to perform wrist flexion of both affected and unaffected hands, without MVF on the monitor screen. In the unilateral MVF with unilateral manual training (UMUT) condition, the participants performed wrist flexion with the unaffected hand while concurrently observing unilateral MVF simulating the movement of the affected hand. In the unilateral MVF with bilateral manual training (UMBT) condition, the participants performed wrist flexion with both the unaffected and affected hands, while the unilateral MVF on the affected side served to guide the motor execution of the affected hand. Lastly, in the bilateral MVF with bilateral manual training (BMBT) condition, the participants performed wrist flexion with both the unaffected and affected hands, and simultaneously observed the bilateral MVF (including both affected and unaffected sides). Statistical analyses of EEG data were computed using the cluster-based non-parametric permutation method.

Supporting Image: MT_paradigm_ohbm_Fin2.jpg

·Figure1. Schematic illustration of task design.

Results:

We focused on alpha (9-14 Hz) oscillatory activity in the affected motor region (i.e., C4 channel) (Figure 2). We found a larger decrease in alpha power for the UMBT compared to BT condition during 243-369 ms (p = .004) and 982-1100 ms (p = .020) relative to the EMG onset, indicating greater cortical engagement of the affected motor regions when unilateral MVF was provided during bilateral movement. We found a smaller decrease in alpha power for the UMBT compared to UMUT condition during 850-951 ms (p = .019), reflecting reduced cortical engagement of the affected motor regions during bilateral movement compared to unilateral movement of the unaffected side when unilateral MVF was provided. Lastly, we found a larger decrease in alpha power for the BMBT compared to UMBT condition during 267-389 ms (p = .011) and 846-991 ms (p = .043), indicating greater cortical engagement induced by bilateral MVF compared to unilateral MVF during bilateral movement.

·Figure2. Time-frequency results of alpha (9 – 14 Hz) power. 0 ms indicates the EMG onset of the unaffected hand. The topography shows the alpha power averaged across 0 – 1100 ms.

Conclusions:

In conclusion, the findings demonstrated that MVF in digital-based MT enhanced alpha power suppression in the central electrodes of the affected hemisphere compared to the condition without MVF. The findings provide neural evidence that MVF facilitates cortical engagement of the affected motor area for stroke patients.

Disorders of the Nervous System:

Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s)

Novel Imaging Acquisition Methods:

EEG ¹

Perception, Attention and Motor Behavior:

Mirror System ²

Motor Planning and Execution

Keywords:

Electroencephaolography (EEG)

Motor

Other - cerebrovascular accident (CVA)

^1|2Indicates the priority used for review

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Rizzo, M., Petrini, L., Del Percio, C., Lopez, S., Arendt‐Nielsen, L., & Babiloni, C. (2022). Mirror visual feedback during unilateral finger movements is related to the desynchronization of cortical electroencephalographic somatomotor alpha rhythms. Psychophysiology, 59(12), e14116.

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