Visual Feedback and Trial-to-Trial Force Variability in Chronic Stroke = Visual Feedback and Trial-to-Trial Force Variability in Chronic Stroke

다국어 초록 (Multilingual Abstract)

Unilateral stroke typically causes deficits in bimanual movements. Although visual information is important for successful force control, stroke survivors may have an impaired capability to process visual information and correct their motor actions across multiple force control trials. This study investigated trial-to-trial variability on bimanual force production patterns in chronic stroke patients while manipulating visual information (i.e., vision versus no vision). Nine chronic stroke patients and nine age-matched healthy controls performed isometric bimanual force control at 25% of maximal voluntary contraction with and without visual information. Across 12 trials, we calculated trial-to-trial variability (coefficient of variation; CV) and variability components (good and bad variability) on mean force, CV on force variability (standard deviation; SD), and CV on force frequency power below 16 Hz. Individuals with a stroke revealed three significant force control deficits across trials: (a) increased trial-to-trial variability on mean force and bad variability in the no vision condition, (b) greater trial-to-trial variability on SD in both vision and no vision conditions, and (c) higher trial-to-trial variability on power below 4 Hz across vision conditions. Our novel findings indicate that constantly producing bimanual force across trials are relatively challenging for chronic stroke patients and these impairments may be associated with impaired visuomotor processing and feedback control.