Al-Izki Sarah, Kirkwood Peter A, Lemon Roger N, Enríquez Denton Manuel
Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom.
Exp Neurol. 2008 Jul;212(1):118-31. doi: 10.1016/j.expneurol.2008.03.020. Epub 2008 Apr 3.
The rubrospinal tract (RST) of the rat is widely used in studies of regeneration and plasticity, but the electrophysiology of its spinal actions has not been described. In anaesthetised rats with neuromuscular blockade, a tungsten microelectrode was located in the region of the red nucleus (RN) by combining stereotaxis with recording of antidromic potentials evoked from the contralateral spinal cord. Single stimuli through this electrode typically elicited two descending volleys in the contralateral dorsolateral funiculus (DLF) separated by about 1 ms, and one volley recorded from the ipsilateral DLF. Latencies of the ipsilateral and the early contralateral volley were similar. The activation of these volleys depended on the location of the stimulation site in or near the RN. Evidence is adduced to show that: (a) the late contralateral volley is carried by fibres of RST neurones, synaptically activated; (b) the early contralateral volley is mostly carried by RST fibres stimulated directly; (c) the ipsilateral volley is sometimes carried by RST fibres from the RN on the side contralateral to the stimulus; (d) otherwise, either early volley may derive from fibres in other tracts. Synaptic potentials related to the volleys were recorded within the cervical enlargement and their distribution plotted on cross-sections of the spinal cord. These measurements suggest that the great majority of RST terminations are on interneurones in the intermediate region contralateral to the RN. Direct synaptic actions on motoneurones are likely to be weak. Stimulation parameters appropriate for specific activation of the RST in future studies are suggested.
大鼠的红核脊髓束（RST）在再生和可塑性研究中被广泛应用，但其脊髓活动的电生理学尚未得到描述。在麻醉且神经肌肉被阻断的大鼠中，通过将立体定位与对侧脊髓诱发的逆向电位记录相结合，将钨微电极置于红核（RN）区域。通过该电极的单次刺激通常在对侧背外侧索（DLF）中引发两个下行波群，间隔约1毫秒，并且在同侧DLF中记录到一个波群。同侧和早期对侧波群的潜伏期相似。这些波群的激活取决于刺激部位在RN内或其附近的位置。有证据表明：（a）晚期对侧波群由RST神经元的纤维传导，通过突触激活；（b）早期对侧波群主要由直接受刺激的RST纤维传导；（c）同侧波群有时由与刺激侧对侧的RN发出的RST纤维传导；（d）否则，任何一个早期波群可能来自其他束中的纤维。在颈膨大内记录了与波群相关的突触电位，并将其分布绘制在脊髓横截面上。这些测量结果表明，绝大多数RST终末位于与RN对侧的中间区域的中间神经元上。对运动神经元的直接突触作用可能较弱。文中还提出了在未来研究中特异性激活RST的合适刺激参数。
