Yamaguchi T
Brain Res. 1986 Jul 30;379(1):125-36. doi: 10.1016/0006-8993(86)90264-7.
The funicular pathways that elicit forelimb stepping were investigated with stimulation and lesion of the cervical white matter in decerebrate cats with the lower thoracic cord transected. We localized cross-sectional areas where stimulation evoked rhythmic motor-nerve discharges imitating those of stepping (fictive locomotion) in the immobilized animal, and further examined whether or not lesions made in the corresponding areas abolished actual locomotor movements. Stimulation of the C3 lateral funiculus (LF) produced fictive locomotion in the ipsilateral forelimb. The effective areas of stimulation were located separately in the dorsolateral funiculus (DLF) and in the ventrolateral funiculus (VLF), while the VLF was more effective than the DLF. Effective stimuli were pulse trains with a frequency of about 30 Hz, with a rather wide pulse duration of about 0.5 ms. Blocking axonal conduction through the lower thoracic cord by cooling reproducibly facilitated fictive locomotion in both amplitude and frequency. In the lesion experiments, forelimb locomotor movements were elicited spontaneously or by stimulation of the mesencephalic locomotor region (MLR). The locomotor movements were abolished by complete lesions of the C2-C3 LFs on both sides, but these remained when either the DLF or the VLF was intact on one side. These findings together suggested that the descending pathways for the activation of the spinal locomotor network of the single forelimb are located ipsilaterally in the DLF as well as in the VLF. Both the DLF and the VLF pathways can initiate locomotion, while the VLF pathways have a higher potential for its initiation. Lesion experiments further showed that cats can walk with both forelimbs, even though the spinal locomotor network of the single forelimb was deprived of its main descending input by unilateral lesions of the LF. However, when the unilateral lesion extended to the medial part of the LF, the bilateral walking was abolished; the limb on the lesioned side showed only rhythmic extension movements without active flexion movements, which was out of phase with the stepping movements on the intact side. This finding suggested that the medial part of the LF is important for producing flexion movements during the swing phase of stepping.
在胸下段脊髓横断的去大脑猫中，通过刺激和损伤颈段白质，研究了引发前肢迈步的缆索通路。我们定位了在固定动物中刺激能诱发模仿迈步（虚构运动）的节律性运动神经放电的横截面积，并进一步检查在相应区域进行损伤是否会消除实际的运动。刺激颈3外侧索（LF）可在同侧前肢产生虚构运动。刺激的有效区域分别位于背外侧索（DLF）和腹外侧索（VLF），而VLF比DLF更有效。有效刺激是频率约为30Hz、脉冲持续时间约为0.5ms的较宽脉冲串。通过冷却阻断胸下段脊髓的轴突传导可重复性地促进虚构运动在幅度和频率上的增加。在损伤实验中，前肢运动可自发引发或通过刺激中脑运动区（MLR）引发。双侧C2 - C3 LF完全损伤可消除运动，但当一侧的DLF或VLF完整时，运动仍然存在。这些发现共同表明，单前肢脊髓运动网络激活的下行通路同侧位于DLF以及VLF中。DLF和VLF通路都可启动运动，而VLF通路启动运动的潜力更高。损伤实验进一步表明，即使单前肢的脊髓运动网络因LF的单侧损伤而失去其主要下行输入，猫仍能用双前肢行走。然而，当单侧损伤扩展到LF的内侧部分时，双侧行走被消除；损伤侧的肢体仅表现出有节律的伸展运动，没有主动的屈曲运动，这与完整侧的迈步运动不同步。这一发现表明，LF的内侧部分对于在迈步摆动期产生屈曲运动很重要。
