Whishaw I Q, Pellis S M, Gorny B, Kolb B, Tetzlaff W
Department of Psychology, University of Lethbridge, Alta., Canada.
Behav Brain Res. 1993 Jul 30;56(1):59-76. doi: 10.1016/0166-4328(93)90022-i.
Although it was once thought that the corticospinal (pyramidal) tract was the main substrate of voluntary movement, the extent to which it is involved in the control of proximal vs. distal musculature, independent finger movements, and movements characteristic of different species of animals now is unclear. The objective of this study was to examine the effects of pyramidal tract lesions on skilled forelimb use in rats. In addition, cell morphology in motor cortex following lesions was examined. Naive and trained rats received unilateral pyramidal sections just rostral to the pyramidal decussation. Performance was assessed and filmed on two reaching tasks. Measures of reaching consisted of success in obtaining food, kinematic analysis of limb trajectory and velocity, and qualitative evaluation of 10 movement components comprising a reach. Pyramidal tract lesions only impaired reaching for single food pellets. Almost all movements comprising a reach, except digit opening, were impaired, including lifting, aiming, pronating and supinating the limb, and releasing food. Although success in limb use was unchanged over the 180 day observation period, there were significant improvements in the qualitative features of limb use. Histologically, the morphology of pyramidal cells in the forelimb area ipsilateral to the lesion seemed normal. Rats with additional damage to adjacent structures, such as the medial lemniscus and olivary complex, were much more severely impaired on the reaching tasks, and displayed similar impairments as judged by qualitative and kinematic measures. The results demonstrate that a number of movements involved in independent limb use are chronically impaired by pyramidal tract lesions in the rat. Nevertheless, significant use of the limb is possible, due perhaps to both the contribution of extrapyramidal motor systems and the influence of the remaining pyramidal system through its extrapyramidal connections. The results not only show that the rat pyramidal tract supports functions very similar to those of primates and thus might provide a good model for some aspects of pyramidal tract dysfunctions, but also they argue that the pyramidal tract is involved in both proximal and distal limb movements.
尽管曾经有人认为皮质脊髓（锥体）束是自主运动的主要基础，但目前尚不清楚它在控制近端与远端肌肉组织、独立手指运动以及不同动物物种特征性运动方面的参与程度。本研究的目的是检验锥体束损伤对大鼠熟练前肢使用的影响。此外，还检查了损伤后运动皮层中的细胞形态。未经验证和经过训练的大鼠在锥体交叉前方接受单侧锥体束横切。在两项够物任务中评估并拍摄其表现。够物的测量包括获取食物的成功率、肢体轨迹和速度的运动学分析，以及对构成一次够物的10个运动成分的定性评估。锥体束损伤仅损害了抓取单个食物颗粒的能力。几乎所有构成一次够物的运动，除了手指张开，均受到损害，包括举起、瞄准、肢体旋前和旋后以及释放食物。尽管在180天的观察期内肢体使用的成功率没有变化，但肢体使用的定性特征有显著改善。组织学上，损伤同侧前肢区域锥体细胞的形态似乎正常。对相邻结构如内侧丘系和橄榄复合体有额外损伤的大鼠在够物任务中受损更严重，并且根据定性和运动学测量显示出类似的损伤。结果表明，大鼠中锥体束损伤会长期损害独立肢体使用中涉及的一些运动。然而，肢体仍有可能大量使用，这可能是由于锥体外运动系统的贡献以及剩余锥体系统通过其锥体外连接的影响。这些结果不仅表明大鼠锥体束支持与灵长类动物非常相似的功能，因此可能为锥体束功能障碍的某些方面提供一个良好的模型，而且还表明锥体束参与近端和远端肢体运动。
