ROLE OF SPINAL CORD INTERNEURONS IN PREPARATION FOR VOLUNTARY LIMB MOVEMENT

脊髓中间神经元在肢体自主运动准备中的作用

• 批准号: 7349332
• 负责人: EBERHARD E FETZ
• 金额: $ 13.2万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7349332
• 关键词: ROLE; SPINAL; CORD; INTERNEURONS; PREPARATION

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Spinal neurons play a crucial role in generating voluntary limb movements. We evaluated the extent to which spinal interneurons are engaged in voluntary movement by documenting their responses in monkeys performing flexion-extension movements about the wrist and reaching movements to retrieve food pellets. Interneurons in upper cervical segments C3-C4 were modulated during one or more of these movements. Half of these C3-C4 neurons received input from motor cortex and could therefore be transmitting cortical motor commands. We also documented the output effects on muscles evoked by intraspinal stimulation at different cervical sites. In behaving monkeys the excitatory and inhibitory post-stimulus effects evoked by single intraspinal stimuli were determined in upper and lower cervical segments. In anesthetized monkeys the movements and muscle responses were mapped systematically with brief trains of stimulation. Most sites evoked responses in multiple muscles, even at threshold for movement. The results to date indicate that the output effects have no simple somatotopic organization relative to spinal anatomy, probably because effects are mediated by stimulating a complex mixture of afferent and descending fibers. Other experiments evaluated the modulation of transmission from afferent fibers and descending pathways. We found evidence that descending commands that generate active wrist movements also evoke presynaptic inhibition in afferent fibers that decreases peripheral input to first-order relay INs. In contrast we found no evidence that descending corticospinal fibers could be influenced by peripheral input. Both patterns of presynaptic inhibition function to prevent re-afferent activity produced by movements from interfering with the accurate control of movement by descending commands.

该子项目是利用 NIH/NCRR 资助的中心拨款提供的资源的众多研究子项目之一。子项目和研究者 (PI) 可能已从另一个 NIH 来源获得主要资金，因此可以在其他 CRISP 条目中出现。列出的机构是中心的机构，不一定是研究者的机构。脊髓神经元在产生自主肢体运动中发挥着至关重要的作用。我们通过记录猴子进行手腕屈伸运动和伸手取回食物颗粒的动作来评估脊髓中间神经元参与随意运动的程度。在这些运动中的一个或多个过程中，上颈段 C3-C4 的中间神经元受到调节。这些 C3-C4 神经元中有一半接收来自运动皮层的输入，因此可以传输皮层运动命令。 我们还记录了不同颈部部位的椎管内刺激对肌肉的输出影响。在行为猴子中，在上颈段和下颈段中测定了单一脊柱内刺激引起的兴奋性和抑制性刺激后效应。在麻醉的猴子中，通过简短的刺激序列系统地绘制出运动和肌肉反应。大多数部位都会引起多块肌肉的反应，甚至在运动阈值时也是如此。迄今为止的结果表明，输出效应没有相对于脊柱解剖学的简单体位组织，可能是因为效应是通过刺激传入纤维和下行纤维的复杂混合物来介导的。 其他实验评估了传入纤维和下行路径的传输调制。我们发现证据表明，产生主动手腕运动的下行命令也会引起传入纤维的突触前抑制，从而减少对一阶中继 IN 的外周输入。相比之下，我们没有发现证据表明下行皮质脊髓纤维可能受到外周输入的影响。两种突触前抑制模式的作用是防止运动产生的再传入活动干扰下行命令对运动的精确控制。