Probable corticospinal tract control of spinal cord plasticity in the rat
Probable corticospinal tract control of spinal cord plasticity in the rat
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DOI：
10.1152/jn.00391.2001
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发表时间：
2002-02-01
影响因子：
2.5
通讯作者：
Wolpaw, JR
中科院分区：
文献类型：
--
作者：
Chen, XY;Wolpaw, JR
从大脑下行的活动在整个生命过程中塑造了脊髓反射功能，但对这种脊髓可塑性的机制知之甚少。操作条件反射的H-反射，脊髓牵张反射的电模拟，是一个简单的模型，研究这些机制。早期在Sprague-Dawley大鼠中进行的研究表明，在同侧柱（LC）（包含红核脊髓束、网状脊髓束和前庭脊髓束）的胸中部横断不能阻止比目鱼肌H反射的操作性条件反射降低的获得，而在背柱（包含主皮质脊髓束（CST）和背柱上行束（DA））的胸中部横断则可以阻止操作性条件反射的获得。本研究探讨了CST或DA横断对H反射减少的影响，以及LC、CST或DA横断对维持既定减少的影响。CST横断前的条件防止收购H反射减少，而DA横断没有这样做。在获得H反射减少后的CST横断导致在10天内逐渐丧失减少，并导致H反射显著大于原始的幼稚H反射。与此相反，LC或DA横断后H-反射减少已收购不影响维持的减少。这些结果，在早期的研究相结合，强烈暗示，在大鼠的皮质脊髓束（CST）是必不可少的收购和维持的操作性条件反射的减少，其他主要的脊髓通路是不必要的。CST功能的这一以前未被认识的方面使人们深入了解运动技能的获得和维持的过程，并可能导致诱导，指导和评估脊髓损伤后功能恢复的新方法。
Descending activity from the brain shapes spinal cord reflex function throughout life, yet the mechanisms responsible for this spinal cord plasticity are poorly understood. Operant conditioning of the H-reflex, the electrical analogue of the spinal stretch reflex, is a simple model for investigating these mechanisms. An earlier study in the Sprague-Dawley rat showed that acquisition of an operantly conditioned decrease in the soleus H-reflex is not prevented by mid-thoracic transection of the ipsilateral lateral column (LC), which contains the rubrospinal, reticulospinal, and vestibulospinal tracts, and is prevented by transection of the dorsal column, which contains the main corticospinal tract (CST) and the dorsal column ascending tract (DA). The present study explored the effects of CST or DA transection on acquisition of an H-reflex decrease, and the effects of LC, CST, or DA transection on maintenance of an established decrease. CST transection prior to conditioning prevented acquisition of H-reflex decrease, while DA transection did not do so. CST transection after H-reflex decrease had been acquired led to gradual loss of the decrease over 10 days, and resulted in an H-reflex that was significantly larger than the original, naive H-reflex. In contrast, LC or DA transection after H-reflex decrease had been acquired did not affect maintenance of the decrease. These results, in combination with the earlier study, strongly imply that in the rat the corticospinal tract (CST) is essential for acquisition and maintenance of operantly conditioned decrease in the H-reflex and that other major spinal cord pathways are not essential. This previously unrecognized aspect of CST function gives insight into the processes underlying acquisition and maintenance of motor skills and could lead to novel methods for inducing, guiding, and assessing recovery of function after spinal cord injury.