DISCHARGE PATTERNS OF MOTONEURONS

这项研究的长期目标是从功能上表征 参与突触前控制的神经元回路 初级传入纤维在哺乳动物脊髓中的作用 以及突触前抑制在感觉运动中所起的作用 整合。为此，我们将追求以下具体目标： 具体目标1：在麻醉或去大脑的猫身上，我们将研究 可能是皮质-脊髓控制的特异性， 节段性通路上的网状脊髓纤维和蓝斑脊髓纤维 介导单个Ia和Ia组初级传入去极化(PAD) IB根据传入纤维的肌肉来源进行传入。这个 皮质-脊髓传入的行为将被更广泛地研究 研究微刺激运动皮质对大鼠大脑皮质运动功能的影响 单Ia和/或Lb纤维对的椎内阈值 到相同或不同的肌肉(屈肌和伸肌)。此外, 将在去大脑的猫身上研究大脑垫图案的变化。 单根Ia和Ib纤维阻断脉冲传导前后 胸髓可逆性降温下行通路。 具体目标2：在麻醉的猫身上，将对垫子进行研究 神经前后功能识别肌肉传入的模式 分割和再生。需要检验的假设是，垫子 在正常Ia和Ib纤维中观察到的模式在神经损伤后重建 再生传入纤维适当重新连接后的损害 外周感受器。 具体目标3：丹参的药理和电生理研究 末级中间核中间神经元的突触作用 I组的传入纤维和运动神经元在麻醉状态下形成 猫。将特别注意测试以下建议： 对这些中间神经元产生的运动神经元的抑制是GABA能的。 将对椎管内分布和功能进行研究 驱动几类背角神经元的网络特征 中间核中间神经元。 具体目标4：将继续在麻醉猫身上进行研究，以进一步 记录观察到的在突触前抑制Ia 单突触EPSPS不会影响由 对下行纤维的刺激。通过反卷积技术，我们 将检验拉伸协同和拮抗肌肉的效果 以及电刺激I组纤维对波幅和 单突触EPSPS分立分量的概率分布 在同一运动神经元中由单个Ia纤维和少量 下行纤维。

The long term goal of this research is to functionally characterize the neuronal circuitry involved in the presynaptic control of the synaptic effectiveness of primary afferent fibers in the mammalian spinal cord, as well as the role played by presynaptic inhibition in sensory motor integration. To this end we will pursue the following specific aims: Specific Aim 1: In anesthetized or decerebrated cats we will study the possible specificity of the control exerted by cortico-spinal, reticulo-spinal and coeruleo-spinal fibers on the segmental pathways mediating the primary afferent depolarization (PAD) of single group Ia and Ib afferents according to the muscle of origin of the afferent fibers. The action of cortico-spinal inputs will be examined more extensively by studying the effects produced by microstimulation of the motor cortex on the intraspinal threshold of pairs of single Ia and/or lb fibers belonging to the same or to different muscles (flexors and extensors). In addition, studies will be made in decerebrate cats of changes in the PAD patterns of single Ia and Ib fibers before and after blocking impulse conduction in descending pathways by reversible cooling of the thoracic spinal cord. Specific Aim 2: In anesthetized cats, studies will be made on the PAD patterns of functionally identified muscle afferents before and after nerve section and regeneration. The hypothesis to be tested is that the PAD patterns observed in normal Ia and Ib fibers are reestablished after nerve lesions following appropiate reconnection of regenerated afferent fibers with peripheral receptors. Specific Aim 3: Pharmacological and electrophysiological studies of the synaptic actions exerted by last-order intermediate nucleus interneurons on group I afferent fibers and motoneurons will be made in anesthetized cats. Particular attention will be given to test the proposal that the inhibition of motoneurons produced by these interneurons is GABAergic. Studies will be made on the intraspinal distribution and functional characteristics of networks of dorsal horn neurons driving several classes of intermediate nucleus interneurons. Specific Aim 4: Studies will continued in anesthetized cats to further document the observation that during presynaptic inhibition of Ia monosynaptic EPSPs there is no effect on monosynaptic EPSPs produced by stimulation of descending fibers. By means of deconvolution techniques we will examine the effects of stretching synergistic and antagonistic muscles as well as of electrical stimulation of group I fibers on the amplitude and probability distribution of the discrete components of monosynaptic EPSPs produced in the same motoneuron by single Ia fibers and by a small number of descending fibers.