DISCHARGE PATTERNS OF MOTONEURONS

本研究的长期目标是功能性地表征 参与突触前控制的神经元回路 哺乳动物脊髓中初级传入纤维的有效性， 以及突触前抑制在感觉运动中的作用 一体化为此，我们将努力实现以下具体目标： 具体目标1：在麻醉或去脑猫中，我们将研究 皮质-脊髓的控制可能具有特异性， 节段性通路上的网状脊髓和蓝斑脊髓纤维 介导单个Ia组的初级传入去极化（PAD）， Ib类传入纤维按肌源性的传入纤维排列。的 皮质脊髓输入的作用将通过以下方法更广泛地检查： 研究微刺激运动皮层对 单Ia和/或Ib纤维对的椎管内阈值属于 相同或不同的肌肉（屈肌和伸肌）。此外，本发明还提供了一种方法， 将在去大脑猫中研究PAD模式的变化， 单Ia和Ib纤维在阻断冲动传导前后， 通过胸脊髓的可逆性冷却下行通路。 具体目标2：在麻醉猫中，将对PAD进行研究 神经前和神经后功能识别的肌肉传入的模式 节和再生。要检验的假设是， 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连后的病变 与外周感受器。 具体目标3：药物和电生理学研究 末级中间核中间神经元的突触作用 对I组传入纤维和运动神经元进行麻醉， 猫将特别注意测试以下建议： 由这些中间神经元产生的运动神经元的抑制是GABA能的。 对椎管内的分布和功能进行研究 背角神经元驱动几类神经元的网络特性 中间核的中间神经元。 具体目标4：将继续在麻醉猫中进行研究，以进一步 记录了在突触前抑制Ia期间的观察结果 单突触EPSPs对单突触EPSPs没有影响， 刺激下行纤维。通过反卷积技术， 将研究拉伸协同肌和拮抗肌的效果 以及I组纤维的电刺激对振幅的影响， 单突触EPSP离散分量的概率分布 在同一运动神经元中由单个Ia纤维和少数Ia纤维产生 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.