Brain Structural And Functional Plastic Study Of Basal Ganglia Stroke During Motor Recovery

Previous studies have shown that structural and functional cerebral reorganization exist during motor recovery of stroke patients,including recruitment of contralesional motor areas,diffusion changes of ipsilesional fiber bundles,functional activation shift of motor control,etc.However,due to the variety of lesion sites,recovery sessions and imaging methods,there is no consistent conclusion of motor recovery mechanism and effictive neuroimaing biomarkers were rately identified across motor recovery in stroke.As an important pathway of motor execution,corticospinal tract(CST)has shown structural changes on stroke patients and the changes are correlated with motor dysfunction.Damage on basal ganglia(BG)not only affect CST integrity,but also has direct impact on cerebellum(CB)and thalamus,both of which involve motor control and motor learning.We combined Diffusion Tensor Imaging(DTI)and functional Magnetic Resource Imaging(fMRI)methodologies to investigate dynamic changes of CST pathway,BG-thalamus-cortical loop,CB-thalamus-cortical loop as well as the correlation of these loops along with motor recovery.We recruited 14 ischemic stroke patients with lesion in BG area to study brain structural and functional changes during motor recovery.Each of the patient performed DTI and fMRI scan for 3 sessions,i.e.within 2 weeks(acute stage,S1),1-3 months(early stage,S2),over 3 months(chronic stage,S3)after stroke.Fugl-Meyer(FM)motor assessment was also acquired and finger-tapping task was performed during fMRI scanning.Regions of interests in this study include bilateral cerebral peduncle(CP),posterior limb of internal capsule(PLIC),superior carona radiate(s CR),cerebellum,thalamus,cingulate gyrus,primary motor area,premotor cortex,and secondary motor area.We calculated diffusion parameters of CST pathway as well as activation level of motor-related regions,and perfomed correlation analysis between them and FM score.From our DTI results,the lateralization of bilateral CST fractional anisotropy(FA)value was positively correlated with FM score during S2,indicating the importance of CST integrity in maintaining good motor function.The FAs in contralesional CP and PLIC during S1 were associated with changes of FM score,showing that motor recovery was dependent on the damage degree of ipsilesional CST.The fMRI results showed CB functional lateralization correlated with motor recovery.The more contralesional dominance of CB activation at S1,the better motor recovery is at S2;whereas S2 showed the opposite trend to predict S3 stage motor function.Significant activation of cingulate gyrus during S2 predicted functional motor recovery of S3,implying the role of attentional modulation.The longitudinal study on motor recovery after stroke consolidates the hypothesis that basal ganglia stroke patients dysfunction in the three mentioned loops.The neuroimaging biomarkers showing significant correlation with motor recovery provide informative target for effective therapeutic intervention.