Electrical stimulation of spared corticospinal axons augments connections with ipsilateral spinal motor circuits after injury
Electrical stimulation of spared corticospinal axons augments connections with ipsilateral spinal motor circuits after injury
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DOI：
10.1523/jneurosci.3489-07.2007
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发表时间：
2007-12-12
影响因子：
5.3
通讯作者：
Martin, John H.
中科院分区：
文献类型：
--
作者：
Brus-Ramer, Marcel;Carmel, Jason B.;Martin, John H.
在发育过程中，活动依赖性竞争塑造了脊髓中皮质脊髓（CS）轴突的生长。神经修复中的一个重要问题是活性是否可以用于促进成熟的CS轴突的生长。受伤后，备用CS轴突发芽并建立新的连接，但往往不足以恢复功能。我们认为，电刺激损伤后的备用轴突将增强发芽和加强与脊髓运动回路的连接。为了研究活动的影响，我们电刺激脊髓锥体中的CS束轴突。为了研究损伤的影响，一个金字塔被破坏。我们研究了稀疏同侧CS预测的完整的锥体作为模型的稀疏连接保留后中枢神经系统损伤。我们确定了CS轴突激活同侧脊髓运动回路的能力，并追踪了它们的脊髓投射。为了了解损伤和活动的单独和组合贡献，我们检查了仅接受刺激、仅接受损伤和损伤加刺激的动物。刺激和损伤单独加强CS连接和增加同侧灰质的生长。损伤后刺激备用轴突促进生长，反映了活动和损伤单独的影响之和。CS终止在脊髓的腹侧运动领土内是denandly，在这些动物中的连接显着强于单独损伤后，表明活动增强损伤诱导的可塑性。我们表明，活动促进可塑性成熟的CS系统和活动和损伤之间的相互作用，优先促进腹侧脊髓运动回路的连接。
Activity-dependent competition shapes corticospinal (CS) axon outgrowth in the spinal cord during development. An important question in neural repair is whether activity can be used to promote outgrowth of CS axons in maturity. After injury, spared CS axons sprout and make new connections, but often not enough to restore function. We propose that electrically stimulating spared axons after injury will enhance sprouting and strengthen connections with spinal motor circuits. To study the effects of activity, we electrically stimulated CS tract axons in the medullary pyramid. To study the effects of injury, one pyramid was lesioned. We studied sparse ipsilateral CS projections of the intact pyramid as a model of the sparse connections preserved after CNS injury. We determined the capacity of CS axons to activate ipsilateral spinal motor circuits and traced their spinal projections. To understand the separate and combined contributions of injury and activity, we examined animals receiving stimulation only, injury only, and injury plus stimulation. Both stimulation and injury alone strengthened CS connectivity and increased outgrowth into the ipsilateral gray matter. Stimulation of spared axons after injury promoted outgrowth that reflected the sum of effects attributable to activity and injury alone. CS terminations were densest within the ventral motor territories of the cord, and connections in these animals were significantly stronger than after injury alone, indicating that activity augments injury-induced plasticity. We demonstrate that activity promotes plasticity in the mature CS system and that the interplay between activity and injury preferentially promotes connections with ventral spinal motor circuits.