Purpose: This study compared the sensory-motor interactions and strategies for whole-body movement in individuals with stroke who had damaged motor system area or sensory system area in the brain.
Methods: Participants with hemiparesis were asked to perform sit-to-stand movements while their vision was restricted, which can affect completion of the task. The participants were divided into two groups. The first group had no history of lesions in the sensory system area but did have a history of lesions in the motor system area (no damaged sensory-system: NDS). The second group had a history of lesions in the sensory system area of the brain (damaged sensory-system: DS). Center-of-pressure (COP) trajectories were measured to evaluate balance control in participants with and without vision, and numbers of sub-movements (i.e. numbers of segmented movements which reflect the degree of use of the feedback loops) were measured to evaluate feedforward and feedback control. Movement times were also measured.
Results: When vision was restricted, NDS participants showed increased variability in mediolateral COP trajectories during movement and utilized mainly feedforward control. In contrast, DS participants showed reduced variability in mediolateral COP trajectories during movement and utilized additional feedback control.
Conclusions: These results demonstrate two types of strategies for whole-body movements in individuals with stroke. These differences may be attributed to whether the individual can compensate for vision with somatic senses and whether appropriate processing of somatosensory information has been lost. Individuals with hemiparesis created dexterous and flexible strategies to execute tasks successfully, depending on the characteristics of their sensorimotor disorders.
Keywords: Dynamic balance control; feed-forward and feed-back control; minimum intervention principle; restricting vision; sit to stand.