DISCHARGE PATTERNS OF MOTONEURONS

描述（申请人摘要）：本研究的长期目标是 已经描述了突触前神经元回路的特征， 哺乳动物初级传入神经突触有效性的控制 并揭示突触前抑制在脊髓中所起的作用， 感觉运动整合 在下一次赠款期间所做的大部分努力 在麻醉或去大脑的情况下， 猫，节段性和棘上性控制的选择性 在介导初级传入去极化（PAD）的通路上的输入， 肌肉和皮肤传入神经。 工作假设是， 传入纤维的椎管内分支不是 信息传输，但代表潜在的路线，可以用来 将信息流引导到不同的神经元集合， 要执行的功能。 为此，感官和 下行输入的途径，导致PAD的两个侧支 单个Ia、Ib或皮肤纤维，一条侧枝终止于 中间核或背角在L 6节段水平，和其他 升到L3水平Clarke氏柱或背侧支 将分别比较柱核。 PAD将从以下推断 每个侧支的椎管内阈值的变化。 差异 影响的大小将归因于作用的选择性 由刺激的两条侧支的通路产生。 的影响 在静息PAD和感觉诱发的PAD上的可逆性脊髓化 和下行刺激的节段（L 6）和上升（L3）侧支， 同样的肌肉或皮肤传入也将被检查，以及 条件反射后Ia纤维中静息和诱发PAD的抑制 刺激皮肤和关节神经。 以前的研究表明，刺激网状细胞， 形成在大量的传入纤维中产生PAD 周围神经挤压后1-3个月与肌梭重新连接。 这些影响归因于脊柱的重组， 通路介导受损纤维的PAD。 这里提出的实验是 设计用于检查i）传入神经中产生的PAD是否与 肌梭与突触前抑制有关ii）GABA能 PAD的性质和突触前抑制产生的 重新连接的传入iii）PAD产生的程度 延髓网状结构的刺激仅限于受损的 （四）其他影响因素可能产生的变化 下行输入（大脑皮层、中缝核和红核）。 第三个项目旨在研究 背角神经元和中间核中间神经元群 介导非相互性突触后抑制（I类）或PAD（I类 II）。 计算技术将用于公开a）脊柱 与课堂自发活动同步出现的潜在能力 I类或II类中间神经元，B）神经元的脊髓位置， 相应的脊髓电位，c）当 诱发的细胞外场电位和神经元间活动 刺激肌肉和皮肤传入神经， （网状脊髓和皮质脊髓）输入之前是脊髓电位 与I类或II类中间神经元的活动相关。 这些 这些问题与理解功能关系有关 脊髓中间神经元的定义集和它们在脊髓中的可能作用之间的关系 由传入纤维传递的信息的调制。

DESCRIPTION (Applicant's abstract): 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 mammalian spinal cord and to disclose the role played by presynaptic inhibition in sensory-motor integration. Most of the effort made during the next grant period will be addressed to document, in the anesthetized or decerebrated cat, the selectivity of the control exerted by segmental and supraspinal inputs on the pathways mediating primary afferent depolarization (PAD) of muscle and cutaneous afferents. The working hypothesis is that the intraspinal branches of afferent fibers are not obliged routes for information transmission but represent potential routes that can be used to direct the information flow to different sets of neurons according to the function to be performed. To this end, the effects of sensory and descending inputs on the pathways leading to PAD of two collaterals of individual Ia, Ib or cutaneous fibers, one collateral ending within the intermediate nucleus or dorsal horn at the L6 segmental level, and the other collateral ascending to Clarke s columns at the L3 level or to the dorsal column nuclei, respectively, will be compared. PAD will be inferred from changes in the intraspinal threshold of each collateral. Differences in the magnitude of the effects will be attributed to selectivity in the action exerted by the stimulated pathways on both collaterals. The effects of reversible spinalization on the resting PAD and on the PAD evoked by sensory and descending stimuli in segmental (L6) and ascending (L3) collaterals of the same muscle or cutaneous afferent will also be examined, as well as the inhibition of the resting and evoked PAD in Ia fibers following conditioning stimulation of cutaneous and joint nerves. Previous investigations have indicated that stimulation of the reticular formation produces PAD in a substantial number of afferent fibers reconnected with muscle spindles 1-3 months after a peripheral nerve crush. These effects have been attributed to a reorganization of the spinal pathways mediating PAD of the damaged fibers. Experiments proposed here are designed to examine i) if the PAD produced in afferents reconnected with muscle spindles is associated with presynaptic inhibition ii) the GABAergic nature of the PAD and of the presynaptic inhibition produced in the reconnected afferents iii) the extent to which the PAD produced by stimulation of the bulbar reticular formation is restricted to the damaged afferents and iv) possible changes in the effects produced by other descending inputs (cerebral cortex, raphe nuclei and red nucleus). A third project aims to examine the functional relationship between populations of dorsal horn neurons and intermediate nucleus interneurons mediating non-reciprocal postsynaptic inhibition (class I) or PAD (class II). Computational techniques will be used to disclose a) the spinal potentials which appear in synchrony with the spontaneous activity of class I or class II interneurons, b) the instraspinal location of the corresponding cord potentials, c) the changes produced when the extracellular field potentials and interneuronal activity evoked by stimulation of muscle and cutaneous afferents and by descending (reticulo-spinal and cortico-spinal) inputs is preceded by cord potentials associated with the activity of class I or class II interneurons. These issues are relevant for the understanding of the functional relationships between defined sets of spinal interneurons and their possible role in the modulation of information conveyed by afferent fibers.