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Okawada M1,2, Kaneko F1,2, Shindo K1,2, Yoneta M1,2,3, Okuyama K1, Akaboshi K1, Liu M1
1Keio University School of Medicine, Department of Rehabilitation Medicine, Shinjuku, Japan, 2Shonan Keiiku Hospital, Department of Rehabilitation, Fujisawa, Japan, 3Keio University Graduate School of Medicine, Department of Rehabilitation Medicine, Shinjuku, Japan
Background: Motor imagery is the mental simulation of a given movement without any overt movement. During motor execution and motor imagery, many neural activities are shared among cortical areas. The power values of electroencephalogram (EEG) with respect to alpha-bands and beta-bands recorded on sensory motor cortex are attenuated by activity during motor execution and motor imagery (event-related desynchronization: ERD). ERD during motor imagery is utilized in a brain-computer interface (BCI). We speculatedthat facilitating the ability of motor imagery in patients with stroke would enhance the therapeutic effect of BCI. Notably, kinesthetic illusion induced by visual stimulation (KiNvis) causes movement perception by visual illusion without accompanying voluntary movement, and causes activity in the premotor cortex, supplementary motor cortex, and inferior parietal cortex. Therefore, KiNvis therapy may affect brain network activity associated with motor imagery.
Purpose: The purpose of this study was to verify whether KiNvis therapy immediately increases ERD during motor imagery in patients with severe upper limb paralysis after stroke.
Methods: This study included 23 patients with severe upper limb paralysis after stroke (14 with right hemiplegia and nine with left hemiplegia). All patients scored 1a for finger movement (no finger extension), as assessed with the Stroke Impairment Assessment Set. This experimental protocol was conducted in accordance with the Helsinki Declaration and was approved by the ethical committee of Shonan Keiiku Hospital. During KiNvis therapy, a pre-recorded movie was projected on the monitor, which was set over the forearm such that the position of the display would provide the illusion that the patient's forearm was identical to that depicted in the movie. The movie showed grasping and opening of the uninvolved hand, and was repeatedly played for 20 min. EEG examination was conducted before and after the intervention. EEG was recorded from damaged hemisphere F3/4 and FC3/4, C3/4, CP3/4, and P3/4. EEG analysis sections were selected as the most reactive frequency bands from among alpha-bands and beta-bands on each channel. For statistical analysis, three-way ANOVA was used to test the effect of “FREQUENCY,” “TIME,” and “LOCATION” factors on ERD. The significance level was set at p 0.05.
Results: There were no significant interactionsamong FREQUENCY, TIME, and LOCATION factors (p=0.350), between FREQUENCYand LOCATION factors (p=0.211), orbetween TIME and LOCATION factors (p=0.279); however, there was a significant interaction between FREQUENCY and TIME factors (p=0.001). In multiple comparisons excluding the LOCATION factor, alpha-band ERD did not change before and after the intervention (p=0.487); however, beta-band ERD increased after the intervention (p=0.001).
Conclusion(s): The results of this study showed that alpha-band ERD did not change, whereas beta-band ERD increased without a location-dependentbecause of this intervention. We suspect that the differences with respect to the physiological characteristics of the EEG frequency affected the results of this study. Beta-band ERDs in a large portion of the brain may represent the effect of KiNvis therapy.
Implications: Because KiNvis therapy rapidly changed EEG characteristics during motor imagery, it can be used as pre-conditioning for BCI therapy or conventional therapy.
Keywords: kinesthetic illusion induced by visual stimulation, event related desynchronization, motor imagery
Funding acknowledgements: This work was supported by the Development of Medical Devices and Systems for Advanced Medical Services by AMED.
Purpose: The purpose of this study was to verify whether KiNvis therapy immediately increases ERD during motor imagery in patients with severe upper limb paralysis after stroke.
Methods: This study included 23 patients with severe upper limb paralysis after stroke (14 with right hemiplegia and nine with left hemiplegia). All patients scored 1a for finger movement (no finger extension), as assessed with the Stroke Impairment Assessment Set. This experimental protocol was conducted in accordance with the Helsinki Declaration and was approved by the ethical committee of Shonan Keiiku Hospital. During KiNvis therapy, a pre-recorded movie was projected on the monitor, which was set over the forearm such that the position of the display would provide the illusion that the patient's forearm was identical to that depicted in the movie. The movie showed grasping and opening of the uninvolved hand, and was repeatedly played for 20 min. EEG examination was conducted before and after the intervention. EEG was recorded from damaged hemisphere F3/4 and FC3/4, C3/4, CP3/4, and P3/4. EEG analysis sections were selected as the most reactive frequency bands from among alpha-bands and beta-bands on each channel. For statistical analysis, three-way ANOVA was used to test the effect of “FREQUENCY,” “TIME,” and “LOCATION” factors on ERD. The significance level was set at p 0.05.
Results: There were no significant interactionsamong FREQUENCY, TIME, and LOCATION factors (p=0.350), between FREQUENCYand LOCATION factors (p=0.211), orbetween TIME and LOCATION factors (p=0.279); however, there was a significant interaction between FREQUENCY and TIME factors (p=0.001). In multiple comparisons excluding the LOCATION factor, alpha-band ERD did not change before and after the intervention (p=0.487); however, beta-band ERD increased after the intervention (p=0.001).
Conclusion(s): The results of this study showed that alpha-band ERD did not change, whereas beta-band ERD increased without a location-dependentbecause of this intervention. We suspect that the differences with respect to the physiological characteristics of the EEG frequency affected the results of this study. Beta-band ERDs in a large portion of the brain may represent the effect of KiNvis therapy.
Implications: Because KiNvis therapy rapidly changed EEG characteristics during motor imagery, it can be used as pre-conditioning for BCI therapy or conventional therapy.
Keywords: kinesthetic illusion induced by visual stimulation, event related desynchronization, motor imagery
Funding acknowledgements: This work was supported by the Development of Medical Devices and Systems for Advanced Medical Services by AMED.
Topic: Neurology: stroke; Neurology
Ethics approval required: Yes
Institution: Shonan Keiiku Hospital
Ethics committee: the ethical committee of Shonan Keiiku Hospital
Ethics number: 17-0001
All authors, affiliations and abstracts have been published as submitted.
