Neurophysiological Analysis of Spinoderebellar Tract Neurones of the Thoracic Segments in Relation to Respiratory Movement

脊髓小脑束(SCT)神经元在每个脊髓节段内有两组神经元，一组有未交叉的，另一组有交叉的上升轴突。为了了解它们之间是否存在功能差异，在呼吸过程中，在胸段检查了通过未交叉和交叉SCT传递到小脑的信息。用戊巴比妥钠(35 mg/kg)麻醉猫，潘库溴铵麻醉后人工换气，记录小脑和高位颈髓逆行激活的未交叉和交叉SCT神经元的活动。通过记录膈神经活动(反映中枢呼吸节律)和胸腔运动来监测节律性呼吸运动。34个SCT神经元与呼吸的某些方面显示节律性活动。22个未交叉的SCT神经元主要位于Clarke‘s柱，其神经活动与呼吸泵周期有关。由于这种节律性在迷走神经切断后仍然存在，但在气胸后消失，因此未交叉的SCT神经元的节律性活动可能是由胸壁流入引起的。另一方面，交叉性SCT神经元的节律活动在气胸后仍存在，且与膈神经活动一致，提示节律起源于中枢；在自主呼吸过程中，部分交叉性SCT神经元的节律性活动减弱或消失，提示交叉性SCT可能整合了中枢和外周输入。

In each spinal segment, there exist two grtoups of spinocerebellar tract (SCT) neurones ; one having uncrossed and the other crossed ascending axons. To see if there is a functional difference between them, the kind of information transmitted to the cerebellum through uncrossed and crosses SCTs was examined in the thoracic segments during respiration. Recordings of activity of uncrossed and crossed SCT neurones identified by antidromic activation from the cerebellum and upper cervical spinal cord were made in the cat anesthetized with pentobarbital sodium (35mg/Kg), and artificially ventilated after being paralyzed with pancuronium bromide. Rhythmic respiratory movement was monitored by recording phrenic nerve activity (reflecting central respiratory rhythm) and by thorax movement.Thirty four SCT neurones showed rhythmic activities in relation to some aspects of respiration. Neural activity of 22 uncrossed SCT neurones located in mainly the Clarke's column was locked to the respiratory pump cycle. Because this rhythmicity still remained even after vagotomy, but disappeared after pneumothorax, rhythmic activity of uncrossed SCT neurones may be caused by inflow from the chest wall. On the other hand, rhythmic activity of crossed SCT neurones remained and coincided with the phrenic nerve activity even after pneumothorax, suggesting the central genesis of the rhythmcity.During spontaneous respiration, rhythmic activity of some crossed SCT neurones, which was clearly seen under artificial ventilation, became weak or disappeared, suggesting that crossed SCT may integrate central and peripheral inputs.