Abstract
Background: Mirror therapy is thought to drive interhemispheric communication, resulting in a balanced activation. We hypothesized that embodied virtual mirror visual feedback (VR-MVF) presented on a computer screen may produce a similar activation. In this proof-of-concept study, we investigated differences in movement-related cortical potentials (MRCPs) in the electroencephalogram (EEG) from different visual feedback of user movements in 1 stroke patient and 13 age-matched adults.Methods: A 60-year-old right-handed (Edinburgh score >95) male ischemic stroke [left paramedian pontine, National Institutes of Health Stroke Scale (NIHSS) = 6] patient and 13 age-matched right-handed (Edinburgh score >80) healthy adults (58 ± 9 years; six female) participated in the study. We recorded 16-electrode electroencephalogram (EEG), while participants performed planar center-out movements in two embodied visual feedback conditions: (i) direct (movements translated to the avatar's ipsilateral side) and (ii) mirror (movements translated to the avatar's contralateral side) with left (direct left/mirror left) or right (direct right/mirror right) arms.Results: As hypothesized, we observed more balanced MRCP hemispheric negativity in the mirror right compared to the direct right condition [statistically significant at the FC4 electrode; 99.9% CI, (0.81, 13)]. MRCPs in the stroke participant showed reduced lateralized negativity in the direct left (non-paretic) situation compared to healthy participants. Interestingly, the potentials were stronger in the mirror left (non-paretic) compared to direct left case, with significantly more bilateral negativity at FC3 [95% CI (0.758 13.2)] and C2 [95% CI (0.04 9.52)].Conclusions: Embodied mirror visual feedback is likely to influence bilateral sensorimotor cortical subthreshold activity during movement preparation and execution observed in MRCPs in both healthy participants and a stroke patient.
Highlights
Post-stroke motor rehabilitation techniques, such as constraintinduced movement therapy [1], require residual movements of the affected limb
In the current proof-of-concept study, we investigated changes in the lateralization of movement-related cortical potentials (MRCPs) in EEGs recorded from a stroke participant and 13 agematched healthy participants performing a reaching task using embodied Virtual reality (VR)-mirror visual feedback (MVF)
Like the well-known readiness potentials, we observe an increase in negativity for all the three conditions with respect to the baseline period, with spatial differences described below. (i) Direct left and direct right showed higher negative activity on the contralateral side, i.e., right (C2, CP2, FC4, C4, and CP4) and left-side electrodes (C1, CP1, FC3, C3, and CP3) compared to the ipsilateral electrodes, respectively. (ii) The contralateral negativity is highest for the direct left condition, with peak negative activity at the C2 electrode, negativity at the Cz electrode (−17.0 ± 1.1 μV at 0.4 s), and negativity at the C1 electrode (−14.5 ± 0.75 at 0.4 s)
Summary
Post-stroke motor rehabilitation techniques, such as constraintinduced movement therapy [1], require residual movements of the affected limb. Movement planning and execution are associated with slow negative potentials at the central electrodes in scalp EEG [11], which is thought to reflect the subthreshold activity of the neural tissue and the regulation of cortical excitability. These potentials are found to be sensitive to brain damage [11,12,13,14]. We hypothesized that embodied virtual mirror visual feedback (VR-MVF) presented on a computer screen may produce a similar activation In this proof-of-concept study, we investigated differences in movement-related cortical potentials (MRCPs) in the electroencephalogram (EEG) from different visual feedback of user movements in 1 stroke patient and 13 age-matched adults
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