Grottel K, Krutki P, Mrówczyński W
Department of Neurobiology, University School of Physical Education, Droga D ebi nska 10, 61 555 Poznan, Poland.
Exp Physiol. 1998 Nov;83(6):737-46. doi: 10.1113/expphysiol.1998.sp004155.
Electrophysiological investigation of neurones in sacral segments of the spinal cord was performed in alpha-chloralose-anaesthetized cats in order to establish whether at least some ascending tract neurones could diverge to three different centres located in the brainstem, the cerebellum or the spinal cord. Recordings of antidromic action potentials from cells in S1 and S2 segments were taken following stimulation of the contralateral gigantocellular nucleus, contralateral restiform body and ipsi- and contralateral grey matter of the C6 spinal segment. Antidromic responses allowed identification of several types of neurones that differed in their pattern of supraspinal or propriospinal projections. In eighteen out of a total of sixty-three neurones triple projections to all the above structures were found. In the majority of cells investigated their axons divided into two branches ascending both ipsi- and contralaterally in the lateral funiculi of the spinal cord. Their cell bodies were distributed in laminae VII-VIII except for a minor group of neurones that projected to the C6 segment only, which were located in laminae V-VI. The latter group also displayed lower values of axonal conduction velocities. Comparison of conduction velocities in proximal and distal parts of axons revealed significant slowing in most, raising the possibility that additional collaterals were present to other spinal or supraspinal centres. Dual and triple projections from most cells in this study suggest that such a divergence may be a more common feature of ascending tract neurones than has been reported before.
为了确定至少一些上行束神经元是否能发散至位于脑干、小脑或脊髓的三个不同中枢，在α-氯醛糖麻醉的猫身上对脊髓骶段的神经元进行了电生理研究。在分别刺激对侧巨细胞细胞核、对侧绳状体以及同侧和对侧C6脊髓节段灰质后，记录S1和S2节段细胞的逆向动作电位。逆向反应有助于识别几种在脊髓上或脊髓自身投射模式上不同的神经元类型。在总共63个神经元中的18个中，发现了对上述所有结构的三重投射。在大多数被研究的细胞中，它们的轴突分成两个分支，在脊髓外侧索同侧和对侧上行。它们的细胞体分布在VII - VIII层，除了一小群仅投射到C6节段的神经元，它们位于V - VI层。后一组神经元的轴突传导速度也较低。对轴突近端和远端传导速度的比较显示，大多数轴突传导速度显著减慢，这增加了存在额外侧支至其他脊髓或脊髓上中枢的可能性。本研究中大多数细胞的双重和三重投射表明，这种发散可能是上行束神经元比以前报道的更为常见的特征。
