DISCHARGE PATTERNS OF MOTONEURONS

运动神经元的放电模式

• 批准号: 2260975
• 负责人: PEDRO N RUDOMIN
• 金额: $ 7.58万
• 依托单位: NATIONAL POLYTECHNIC INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-12-01 至 1997-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2260975
• 关键词: afferent nerve; antidromic impulse; cats; cerebellar cortex; cerebral cortex; dorsal column; dorsal horn; dorsal motor nucleus; electrical potential; electrostimulus; evoked potentials; gamma aminobutyrate; gastrocnemius muscle; interneurons; microelectrodes; micromanipulator; motor neurons; neural information processing; neuromuscular transmission; peripheral nervous system; sensorimotor system; synapses

The long term goal of this research has been to characterize the neuronal circuitry involved in the presynaptic control of the synaptic effectiveness of primary afferents in the vertebrate spinal cord and the role played by presynaptic inhibition in sensory-motor integration. The proposed experiments are aimed to disclose the selectivity of the supraspinal control exerted on the spinal pathways mediating the primary afferent depolarization (PAD) of individual muscle spindle and tendon organ afferents and how this control is modified following a peripheral nerve lesions. The following hypothesis will be tested: 1. The synaptic effectiveness of the segmental and ascending collaterals of the same muscle afferent can be selectively controlled by supraspinal structures. We will examine the effects produced by intracortical and surface anodal stimulation of the cerebral and cerebellar cortex and of the bulbar reticular formation on the intraspinal threshold of two collaterals of the same afferent fiber, one in the intermediate and/or motor nucleus and the other in Clarks's column or in the dorsal column nuclei. 2. The last-order GABAergic interneurons that mediate PAD comprise at least two functionally distinct subpopulations of neurons. Experiments will be made to a) establish the synaptic (GABAergic) nature of the monosynaptic PAD produced by graded intraspinal microstimulation either in one or in two collaterals of the same muscle afferent fiber, and b) to characterize the segmental and descending inputs acting on the last-order GABAergic interneurons that are activated by the intraspinal microstimulation. 3. The changes in PAD patterns that are produced after crushing a peripheral nerve are restricted to the lesioned afferent fibers. We have shown that stimulation of the bulbar reticular formation (RF) produces very little PAD in intact muscle spindle afferents. However, 1-3 months after a peripheral nerve crush., RF stimulation produces large PAD in afferent fibers reconnected with muscle spindles. The selectivity of these changes will be tested by recording the PAD elicited by at least two different descending inputs (reticulo- and cortico-spinal) on lateral and medial (MG) gastrocnemius afferents in preparations in which only the MG nerve was crushed 1-3 months previously. We will also examine if the PAD produced at that time is associated with presynaptic inhibition. 4. The PAD-mediating interneurons and the intermediate nucleus interneurons mediating the nonreciprocal inhibition are associated with different subpopulations of dorsal hon neurons. Previous work has shown that there are at least two subpopulations of intermediate nucleus interneurons mediating non-reciprocal inhibitory actions. One of them produces only postsynaptic glycinergic inhibition and the other pre- and postsynaptic GABAergic inhibition. By recording the intraspinal field potentials that are associated to the activity of single interneurons and the interactions of these potentials with potentials produced by stimulation of segmental and descending pathways, we will be able to disclose the functional relationship between individual interneurons and other sets of spinal neurons.

这项研究的长期目标是表征神经元 参与突触有效性的突触前控制的回路 初级传入神经在脊椎动物脊髓中的作用， 感觉-运动整合中的突触前抑制。 拟议 实验的目的是揭示选择性的脊髓上的 对介导初级传入的脊髓通路施加的控制 单个肌梭和腱器官的去极化（PAD） 以及这种控制如何在外周神经后被修改 病变 将检验以下假设： 1. 节段性和上行性侧枝的突触效应 同一肌肉传入神经的传入可以被棘上神经选择性地控制， 结构. 我们将研究皮层内和皮层外神经元的作用。 大脑和小脑皮层的表面阳极刺激以及 两条络脉椎管内阈上的延髓网状结构 同一传入纤维，一个在中间和/或运动核 另一条位于Clarks氏柱或背柱核。 2. 介导PAD的末级GABA能中间神经元包括 至少两个功能不同的神经元亚群。 实验 将被用于a）建立突触（GABA能）的性质， 单突触PAD由分级的椎管内微刺激产生， 同一肌肉传入纤维的一个或两个侧支，和B） 描述作用于最后一阶的分段输入和降序输入 GABA能中间神经元被脊髓内 微刺激 3. 在破碎后产生的PAD模式的变化， 周围神经仅限于受损的传入纤维。 我们有 显示刺激延髓网状结构（RF）产生非常 在完整的肌梭传入中有少量PAD。 然而，1-3个月后， 周围神经损伤RF刺激在传入神经中产生大的PAD 纤维与肌梭重新连接。 这些变化的选择性 将通过记录由至少两种不同的 外侧和内侧（MG）下行输入（网状和皮质脊髓） 腓肠肌传入的准备，其中只有MG神经是 1-3个月前粉碎。 我们亦会研究是否在 这个时间与突触前抑制有关。 4. PAD介导的中间神经元和中间核 介导非交互性抑制的中间神经元与 背神经元的不同亚群。 以前的工作表明 至少有两个中间核亚群 介导非相互抑制作用的中间神经元。 其中一 仅产生突触后甘氨酸能抑制，而其他前和 突触后GABA能抑制。 通过记录脊柱内野 与单个中间神经元的活动相关的电位， 这些电势与 刺激节段和下行通路，我们将能够 揭示了个体中间神经元之间的功能关系， 其他的脊髓神经元