Kanagal Srikanth G, Muir Gillian D
Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
Exp Neurol. 2009 Mar;216(1):193-206. doi: 10.1016/j.expneurol.2008.11.028. Epub 2008 Dec 11.
The purpose of this research was to investigate whether pathways in the dorsal part of the lateral spinal funiculus (DLF) can compensate for loss of corticospinal input (CST) to the spinal cord. The CST is known to control skilled limb movements in rats. The DLF contains several different pathways, including the rubrospinal tract (RST) which is also thought to influence limb movements. After lesions of either the corticospinal or the rubrospinal system, it is unclear how much of the remaining forelimb function is due to the presence of the alternate pathway. To begin to address this issue, the present study investigates the compensatory role of pathways in the DLF, including the rubrospinal tract, after bilateral lesions of the pyramidal tract (PT). We initially performed bilateral PT lesions in rats, which effectively removed the CST input to the spinal cord. We tested these rats during overground locomotion, skilled locomotion and skilled forelimb usage. After a 6 week recovery period, we then performed bilateral DLF lesions and compared the behavioural abilities of these rats to those of animals which underwent simultaneous PT and DLF lesions. If DLF pathways do compensate for PT lesions, then animals with PT lesions would rely more on DLF pathways than animals without PT lesions. Thus we hypothesized that animals with DLF lesions which were performed 6 weeks after PT lesions would exhibit more deficits on several behavioural tasks compared to animals which received PT and DLF lesions simultaneously. Our hypothesis was supported only for skilled pellet retrieval. Hence some DLF pathways, including the RST, were able to compensate for loss of CST input during skilled reaching but not during overground or skilled locomotion in PT-lesioned rats. These differential responses suggest that behavioural tasks vary in their reliance on specific pathways after injury, and, furthermore, that compensation for loss of specific connections can arise from numerous sources.
本研究的目的是调查脊髓外侧索背侧部分（DLF）的通路是否能够补偿脊髓皮质脊髓输入（CST）的丧失。已知CST可控制大鼠的熟练肢体运动。DLF包含几种不同的通路，包括红核脊髓束（RST），其也被认为会影响肢体运动。在皮质脊髓或红核脊髓系统受损后，尚不清楚剩余的前肢功能中有多少是由于替代通路的存在。为了开始解决这个问题，本研究调查了在锥体束（PT）双侧损伤后DLF中的通路，包括红核脊髓束的代偿作用。我们最初在大鼠中进行了双侧PT损伤，这有效地消除了脊髓的CST输入。我们在地面运动、熟练运动和熟练前肢使用过程中对这些大鼠进行了测试。在6周的恢复期后，我们接着进行了双侧DLF损伤，并将这些大鼠的行为能力与同时接受PT和DLF损伤的动物进行了比较。如果DLF通路确实能补偿PT损伤，那么有PT损伤的动物将比没有PT损伤的动物更多地依赖DLF通路。因此，我们假设在PT损伤6周后进行DLF损伤的动物与同时接受PT和DLF损伤的动物相比，在几项行为任务上会表现出更多的缺陷。我们的假设仅在熟练取食实验中得到支持。因此，一些DLF通路，包括RST，能够在PT损伤的大鼠进行熟练抓握时补偿CST输入的丧失，但在地面或熟练运动时则不能。这些不同的反应表明，行为任务在损伤后对特定通路的依赖程度不同，此外，对特定连接丧失的补偿可能来自多种来源。
