大鼠健侧C7移位后大脑皮层可塑性变化的fMRI研究

目的研究大鼠健侧C7移位后跨大脑两半球可塑性的动态变化。方法SD大鼠42只,随机分为正常对照组和手术组,手术组又分为术后2、8、16、20、28、40周组,每组6只,左侧肢体为患侧(全臂丛神经根性撕脱伤),右侧肢体为健侧。建立全臂丛神经根性撕脱伤模型,一期施行健侧C7神经根移位术,通过BOLD成像技术来观察移位术后双侧大脑皮层可塑性变化。结果术后2周、8周刺激患肢前爪,fMRI显示双侧大脑皮层无激活区出现;术后16周在同侧皮层出现激活区,对侧皮层无激活区出现;术后20周同侧皮层有激活区,激活区较16周激活区大,对侧皮层仍无激活区出现;术后28周对侧皮层和同侧皮层均有激活区出现,对侧皮层为1个激活区,同侧皮层多个激活区;术后40周同侧皮层无激活区出现,对侧皮层激活区高度集中,只有一个。结论健侧C7移位后可以成功实现跨正常大脑两半球的功能重组,但其机制与神经通路尚不明确。

Functional MRI study on changes of cross-hemispherical brain plasticity following contralateral C7 transfer

Objective To study changes of cross-hemispherical brain plasticity after contralateral C_7 transfer via functional MRI. Methods 42 adult SD rats were randomly divided into 7 groups: control group and post-operative 2, 8, 16, 20, 28, and 40 week groups, with 6 each. The left side was the contralateral side, and the right side healthy side. Roots of the brachial plexus within the vertebral canal were exposed by semi-laminectomy via posterior approach. Avulsion of all the nerve roots of the brachial plexus was created. After that contralateral C_7 transfer was performed at the same time. fMRI was performed in each group to observe the transformation of brain plasticity following nerve transfer. Results No activated voxels were elicited in both cerebral cortex after stimulation of forepaw of the injuried limb 2 and 8 weeks postoperatively. At 16 weeks there was small activated voxels in the ipsilateral hemisphere (defined as hemisphere ipsilateral to the injured side), but no activated voxels in the contralateral hemisphere (defined as hemisphere contralateral to the injured side). At 20 weeks there was one activated voxels in the ipsilateral hemisphere, while activated voxels were seen in both cortex at 28 weeks. At 40 weeks there was no activated voxels in the ipsilateral hemisphere but one was seen in the contralateral hemisphere. Conclusion Coss-hemispherical functional reorganization does occur following successful C_7 transfer, although its mechanism and pathways of brain plasticity are still unknown.