Cervical sprouting of corticospinal fibers after thoracic spinal cord injury accompanies shifts in evoked motor responses
Cervical sprouting of corticospinal fibers after thoracic spinal cord injury accompanies shifts in evoked motor responses
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DOI：
10.1016/s0960-9822(01)00535-8
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发表时间：
2001-11-13
期刊：
影响因子：
9.2
通讯作者：
Brösamle, C
中科院分区：
文献类型：
--
作者：
Fouad, K;Pedersen, V;Brösamle, C
高等脊椎动物的成年中枢神经系统（CNS）在创伤性损伤后表现出有限的自我修复能力，导致持久的功能缺陷[1]。小的损伤可能导致短暂的损伤，但恢复的机制知之甚少[2]。在皮层水平，感觉和运动表征图的重排通常与恢复平行[3，4]。在感觉系统中，研究表明皮质和皮质下机制有助于地图重排[5，6]，但对于运动系统，情况不太清楚。在这里，我们表明，大规模的结构变化，在备用的喙部脊髓同时发生的后肢运动皮层代表创伤性脊髓损伤后的变化。通过皮质内微刺激，我们定义了一个皮质区，一贯和专门产生后肢肌肉反应，在正常成年大鼠。四周后，双侧横切皮质脊髓束（CST）在下胸脊髓，我们再次刺激这个皮质领域，发现前肢，胡须，躯干的反应，从而证明重组的皮质运动代表。顺行追踪的皮质脊髓纤维起源于这个前后肢区显示，发芽大大增加了正常情况下少量的侧支，导致颈脊髓喙部的病变。我们的结论是，皮质脊髓运动系统有更大的潜力，以适应结构的病变比以前认为，并假设这种自发的生长反应是观察到的运动代表重排的基础上，并有助于功能恢复后不完全病变。
The adult central nervous system (CNS) of higher vertebrates displays a limited ability for self repair after traumatic injuries, leading to lasting functional deficits [1]. Small injuries can result in transient impairments, but the mechanisms of recovery are poorly understood [2]. At the cortical level, rearrangements of the sensory and motor representation maps often parallel recovery [3, 4]. In the sensory system, studies have shown that cortical and subcortical mechanisms contribute to map rearrangements [5, 6], but for the motor system the situation is less clear. Here we show that large-scale structural changes in the spared rostral part of the spinal cord occur simultaneously with shifts of a hind-limb motor cortex representation after traumatic spinal-cord injury. By intracortical microstimulation, we defined a cortical area that consistently and exclusively yielded hind-limb muscle responses in normal adult rats. Four weeks after a bilateral transsection of the corticospinal tract (CST) in the lower thoracic spinal cord, we again stimulated this cortical field and found forelimb, whisker, and trunk responses, thus demonstrating reorganization of the cortical motor representation. Anterograde tracing of corticospinal fibers originating from this former hind-limb area revealed that sprouting greatly increased the normally small number of collaterals that lead into the cervical spinal cord rostral to the lesion. We conclude that the corticospinal motor system has greater potential to adapt structurally to lesions than was previously believed and hypothesize that this spontaneous growth response is the basis for the observed motor representation rearrangements and contributes to functional recovery after incomplete lesions.