Departments of Pain Management and Neurosciences, Anethesiology Institute, Cleveland Clinic, 9500 Euclid Avenue/C25, Cleveland, OH 44195, USA.
Exp Brain Res. 2011 Sep;214(1):151-61. doi: 10.1007/s00221-011-2816-7. Epub 2011 Aug 21.
Descending control is critically important for the generation of locomotor activities. Yet, our understanding of the descending control system of locomotion is limited. We hypothesized that stimulation of the ventrolateral funiculus (VLF) induces rhythmic activity in lumbar neurons that is correlated with locomotor-like activity in the neonatal rat. Intracellular recordings were conducted in the L2-L3 lumbar segments, while locomotor-like output was monitored in the L2 and L5 ventral roots. Stimulation of the VLF at thoracic segments induced locomotor-like activity in the L2 and L5 ventral roots in majority of the preparations (26/33). In a few midline split cord preparations (4/13), VLF stimulation induced rhythmic locomotor-like bursts in either L2 or L5 ventral root without alternating pattern between the ventral roots. The response latencies suggest that VLF stimulation induced antidromic activation (<1 ms, 8 cells), monosynaptic activation (1-3 ms, 18 cells), and oligosynaptic activation (3.5-5 ms, 14 cells) of segmental neurons in the lumbar region. VLF stimulation induced rhythmic membrane potential oscillations with or without bursting of action potentials in 9 of 40 putative interneurons. The membrane potential oscillations were in phase with the locomotor-like output of the L2 ventral root in 7 of the 9 cells while the other 2 cells oscillated in phase with the L5 ventral root activity. We have thus demonstrated that descending axons exist in the VLF which make synaptic connections with segmental neurons in the lumbar region that may be a critical element of the locomotor neural network for the initiation of locomotion.
下行控制对于产生运动活动至关重要。然而，我们对运动的下行控制系统的理解是有限的。我们假设刺激腹外侧索（VLF）会在腰神经元中诱导节律性活动，这种活动与新生大鼠的类似运动活动相关。在 L2-L3 腰段进行细胞内记录，同时在 L2 和 L5 腹根监测类似运动的输出。在胸段刺激 VLF 会引起大多数准备中的 L2 和 L5 腹根的类似运动活动（26/33）。在少数中线分裂脊髓的准备中（4/13），VLF 刺激会在 L2 或 L5 腹根中诱导节律性类似运动爆发，而在腹根之间没有交替模式。反应潜伏期表明，VLF 刺激诱导了节段性神经元的逆行激活（<1ms，8 个细胞）、单突触激活（1-3ms，18 个细胞）和多突触激活（3.5-5ms，14 个细胞）。VLF 刺激在 40 个假定中间神经元中的 9 个中诱导节律性膜电位振荡，伴有或不伴有动作电位爆发。在 7 个细胞中，膜电位振荡与 L2 腹根的类似运动输出相位一致，而另外 2 个细胞与 L5 腹根活动相位一致。因此，我们已经证明，下行轴突存在于 VLF 中，它们与腰区的节段性神经元建立突触连接，这可能是启动运动的运动神经网络的关键组成部分。
