Résumé
After stroke, the less affected upper-limb shows slight but substantial and longterm motor deficits [1]. Kinematically, this is reflected by an increased segmentation of movements. Here, we aim to define how these changes in behavior are accompanied by changes in brain activation.
Twenty-one sub-acute post-stroke patients with a first-ever unilateral ischemic stroke of the middle cerebral artery participated in this study twice: within the first 6 weeks post-stroke and after 6 weeks of rehabilitation. Participants performed a self-paced flexion/extion of the elbow with the less-affected upper-limb. Its kinematic features were analysed and related to the observed fMRI activations during task execution. Results were compared with those of 12 healthy controls with no history of neurological or orthopeadic disease.
Initially, post-stroke patients showed an extended activation of the primary sensorimotor cortex, with an additional recruitment of both the middle temporal and rolandic opercularis areas. After intervention, the rolandic opercularis which is involved in movement visualization [2] remained activated.
Movements of the less affected upper-limb were not only atypical in motor outcome, but were also abnormally controlled. This indicates a disturbance of the bihemispheric motor network that is marked by:
– an overload of the non-damaged hemisphere;
– the employment of alternative control strategies to ensure optimal task execution.