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journal contribution
posted on 2023-01-13, 21:15 authored by Jordan Williamson, Andrew Sikora, Shirley James, Nishaal Parmar, Louis Lepak, Carolyn Cheema, Hazem H. Refai, Dee Wu, Evgeny Sidorov, Julius P. A. Dewald, Yuan Yang

The cortical motor system can be reorganized following a stroke, with increased recruitment

of the contralesional hemisphere. However, it is unknown whether a similar hemispheric shift

occurs in the somatosensory system to adapt to this motor change, and whether this is related to

movement impairments. This proof-of-concept study assessed somatosensory evoked potentials

(SEPs), P50 and N100, in hemiparetic stroke participants and age-matched controls using highdensity

electroencephalograph (EEG) recordings during tactile finger stimulation. The laterality

index was calculated to determine the hemispheric dominance of the SEP and re-confirmed with

source localization. The study found that latencies of P50 and N100 were significantly delayed

in stroke brains when stimulating the paretic hand. The amplitude of P50 in the contralateral (to

stimulated hand) hemisphere was negatively correlated with the Fügl–Meyer upper extremity motor

score in stroke. Bilateral cortical responses were detected in stroke, while only contralateral cortical

responses were shown in controls, resulting in a significant difference in the laterality index. These

results suggested that somatosensory reorganization after stroke involves increased recruitment of

ipsilateral cortical regions, especially for the N100 SEP component. This reorganization delays the

latency of somatosensory processing after a stroke. This research provided new insights related to the

somatosensory reorganization after stroke, which could enrich future hypothesis-driven therapeutic

rehabilitation strategies from a sensory or sensory-motor perspective.


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