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TASK-SPECIFIC EFFECTS ON BRAIN ACTIVITY AFTER STROKE
Abstract
Background and Aims
Evidence supports cortical reorganization in sensorimotor areas induced by constraint-induced movement therapy (CIMT). However, little is known about how task specificity during training affects cortical reorganization. This provoked us to retrospectively analyze an imaging dataset from chronic stroke survivors before and after participation in the signature CIMT protocol. This retrospective analysis aims to evaluate the functional brain activation changes during a precision and a power grasp task in chronic stroke survivors who received two-weeks of CIMT compared to a control group.
Methods
Before and after a 2-week period, 14 chronic stroke survivors, randomized to CIMT (n=8) or non-CIMT (n=6), underwent functional MRI (fMRI). During scan runs, a precision and a power grasp tasks were performed. Pre to post changes in laterality index (LI) were compared by group and task, using a multiple linear regression, for two predetermined motor regions of interest: dorsal premotor cortex (PMd) and primary motor cortex (MI).
Results
Compared to the non-CIMT control group, two weeks of task specific training produced a greater shift in functional activation toward the dorsal premotor region of the lesioned hemisphere during the precision grasp task in the CIMT group (F(4,20)=4.65, p=0.012, adj. R2=32.3%). However, no changes in LI were observed in MI for either task or group (F(4,20)=1.05, p=0.389, adj. R2=0.72%).
Conclusions
Intense progressive precision grasp training drives recovery-supportive functional plasticity in the dorsal premotor cortex of the lesioned hemisphere. The results provide strong evidence for the principle of specificity and intensity of experience-dependent plasticity in stroke survivors.