运动模式期间具有平衡兴奋和抑制的运动前脊髓网络对结构分裂具有高弹性。
Premotor spinal network with balanced excitation and inhibition during motor patterns has high resilience to structural division.
机构信息
Faculty of Health and Medical Sciences, Department of Neuroscience and Pharmacology, University of Copenhagen, DK-2200 KBH N, Denmark.
出版信息
J Neurosci. 2014 Feb 19;34(8):2774-84. doi: 10.1523/JNEUROSCI.3349-13.2014.
Direct measurements of synaptic inhibition (I) and excitation (E) to spinal motoneurons can provide an important insight into the organization of premotor networks. Such measurements of flexor motoneurons participating in motor patterns in turtles have recently demonstrated strong concurrent E and I as well as stochastic membrane potentials and irregular spiking in the adult turtle spinal cord. These findings represent a departure from the widespread acceptance of feedforward reciprocal rate models for spinal motor function. The apparent discrepancy has been reviewed as an experimental artifact caused by the distortion of local networks in the transected turtle spinal cord. We tested this assumption in the current study by performing experiments to assess the integrity of motor functions in the intact spinal cord and the cord transected at segments D9/D10. Excitatory and inhibitory synaptic inputs to motoneurons were estimated during rhythmic motor activity and demonstrated primarily intense inputs that consisted of qualitatively similar mixed E/I before and after the transection. To understand this high functional resilience, we used mathematical modeling of networks with recurrent connectivity that could potentially explain the balanced E/I. Both experimental and modeling data support the concept of a locally balanced premotor network consisting of recurrent E/I connectivity, in addition to the well known reciprocal network activity. The multifaceted synaptic connections provide spinal networks with a remarkable ability to remain functional after structural divisions.
直接测量脊髓运动神经元的突触抑制(I)和兴奋(E)可以深入了解运动前网络的组织。最近对参与海龟运动模式的屈肌运动神经元的这种测量表明,成年海龟脊髓中存在强烈的并发 E 和 I 以及随机膜电位和不规则放电。这些发现与广泛接受的脊髓运动功能前馈互易率模型背道而驰。这种明显的差异被认为是截瘫海龟脊髓中局部网络扭曲造成的实验假象。我们在当前的研究中通过进行实验来评估完整脊髓和 D9/D10 段截断脊髓的运动功能的完整性来检验这一假设。在节律性运动活动期间估计运动神经元的兴奋性和抑制性突触输入,并在截瘫前后主要显示由混合 E/I 组成的强烈输入。为了理解这种高功能弹性,我们使用具有递归连接的网络数学模型来解释平衡的 E/I。实验和建模数据都支持由递归 E/I 连接组成的局部平衡运动前网络的概念,除了众所周知的互易网络活动。多方面的突触连接为脊髓网络在结构分裂后保持功能提供了显著的能力。