Structural And Functional Plasticity Associated With Rehabilitation Intervention In Chronic Stroke

Backgrounds and Purpose:It has been demonstrated that rehabilitative intervention can promote motor recovery in stroke patients. However, little is known regarding the neural mechanisms that underlie rehabilitation treatments. Functional magnetic resonance imaging (fMRI) has the advantages of no damage, high spatial resolution and repeatable research.The aim of this study is to investigate the neural mechanisms that underlie rehabilitation intervention of stroke by using fMRI technique.Methods:Twelve chronic stroke patients with subcortical lesions in the left motor pathway participated in a 4-week rehabilitation intervention and underwent structural and resting-state fMRI scanning before and after the intervention. Both voxel-based morphometry (VBM) and functional connectivity analysis of the ipsilesional (left) primary motor cortex (Ml) were performed in both the stroke patients and healthy controls (HC).Results:(1) Compared with the HC, the stroke patients before and after the intervention both had significant reductions of the gray matter volume in the ipsilesional sensorimotor cortex (SMC), superior parietal lobule, middle frontal gyrus, middle temporal gyrus, and contralesional SMC, superior parietal lobule; but significant increase of the gray matter volume in the ipsilesional basal ganglia, cerebellum. Moreover, comparing between post-and pre-intervention, there were no significant increased or decreased volume of brain regions. (2) Compared with the HC, the decreased connectivity of the ipsilesional M1 with the contralesional SMC, bilateral supplementary motor areas, and inferior parietal lobule were remarkably restored after the intervention. More specifically, the lateralization index of the bilateral SMC tended to be the normal level. Moreover, comparing post-with pre-intervention, we observed significantly increased connectivity of the ipsilesional M1 with the contralesional M1 and medial superior frontal gyrus (mSFG). Additionally, the index of pre-intervention connectivity with the contralesional mSFG was positively correlated with motor improvement.Conclusions:(1) The short duration of four-week rehabilitation intervention was not capable of restoring the brain structure damage induced by stroke. (2) The effects of rehabilitation intervention on intrinsic functional connectivity patterns throughout the brain can be measurable by resting-state fMRI. Our results suggest that the positive effects of rehabilitation on motor recovery are mainly due to restore the symmetry of the functional connectivity pattern between the left and right SMC, as well as simultaneously increase the connectivity with the motor cognitive cortices.