摘要
The three-phase Enriched Environment(EE)paradigm has been shown to promote post-stroke functional improvement,but the neuronal mechanisms are still unclear.In this study,we applied a multimodal neuroimaging protocol combining magnetic resonance imaging(MRI)and positron emission tomography(PET)to examine the effects of post-ischemic EE treatment on structural and functional neuroplasticity in the bilateral sensorimotor cortex.Rats were subjected to permanent middle cerebral artery occlusion.The motor function of the rats was examined using the DigiGait test.MRI was applied to investigate the EE-induced structural modifications of the bilateral sensorimotor cortex.[^(18)F]-fluorodeoxyglucose PET was used to detect glucose metabolism.Blood oxygen level-dependent(BOLD)-functional MRI(fMRI)was used to identify the regional brain activity and functional connectivity(FC).In addition,the expression of neuroplasticity-related signaling pathways including neurotrophic factors(BDNF/CREB),axonal guidance proteins(Robo1/Slit2),and axonal growth-inhibitory proteins(NogoA/NgR)as well as downstream proteins(RhoA/ROCK)in the bilateral sensorimotor cortex were measured by Western blots.Our results showed the three-phase EE improved the walking ability.Structural T2 mapping imaging and diffusion tensor imaging demonstrated that EE benefited structure integrity in the bilateral sensorimotor cortex.PET-MRI fused images showed improved glucose metabolism in the corresponding regions after EE intervention.Specifically,the BOLD-based amplitude of low-frequency fluctuations showed that EE increased spontaneous activity in the bilateral motor cortex and ipsilateral sensory cortex.In addition,FC results showed increased sensorimotor connectivity in the ipsilateral hemisphere and increased interhemispheric motor cortical connectivity and motor cortical-thalamic connectivity following EE intervention.In addition,a strong correlation was found between increased functional connectivity and improved motor performance of limbs.Specifically,EE re
基金
supported by the National Natural Science Foundation of China(82174471).
