Initiation of segmental locomotor-like activities by stimulation of ventrolateral funiculus in the neonatal rat
Initiation of segmental locomotor-like activities by stimulation of ventrolateral funiculus in the neonatal rat
复制标题
DOI：
10.1007/s00221-011-2816-7
复制
发表时间：
2011-09-01
影响因子：
2
通讯作者：
Magnuson, David S. K.
中科院分区：
文献类型：
--
作者：
Cheng, Jianguo;Magnuson, David S. K.
下行控制对于运动活动的产生至关重要。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，腹外侧索（VLF）的刺激诱导腰椎神经元的节律性活动，这与运动样活动在新生大鼠。在L2-L3腰椎节段进行细胞内记录，而在L2和L5前根监测运动样输出。刺激胸段VLF在大多数制备物中诱导L2和L5前根中的运动样活动（26/33）。在少数（4/13）中线分离脊髓标本中，VLF刺激在L2或L5前根中诱导节律性运动样爆发，而前根之间没有交替模式。反应潜伏期表明，VLF刺激引起腰区节段神经元逆向激活（< 1 ms，8个细胞）、单突触激活（1-3 ms，18个细胞）和寡突触激活（3.5-5 ms，14个细胞）。VLF刺激诱导有节奏的膜电位振荡与或没有爆发的动作电位在9个40假定的中间神经元。9个细胞中有7个细胞的膜电位振荡与L2腹根的运动样输出同相，而另外2个细胞的振荡与L5腹根的活动同相。因此，我们已经证明，下行轴突存在于VLF中，其与腰椎区域中的节段性神经元形成突触连接，这可能是运动神经网络启动运动的关键要素。
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.