Modulation of synaptic transmission from segmental afferents by spontaneous activity of dorsal horn spinal neurones in the cat
Modulation of synaptic transmission from segmental afferents by spontaneous activity of dorsal horn spinal neurones in the cat
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DOI：
10.1111/j.1469-7793.2000.00445.x
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发表时间：
2000-12-01
影响因子：
5.5
通讯作者：
Rudomin, P
中科院分区：
文献类型：
--
作者：
Manjarrez, E;Rojas-Piloni, JG;Rudomin, P
1.在麻醉猫中，我们研究了产生自发性负脊髓背电位（nCDPs）的神经元集合对介导皮肤和I组肌肉传入的初级传入去极化（PAD）的节段性通路以及对脊髓运动神经元的Ia单突触激活的影响。与自发nCDPs相关的场电位的椎管内分布表明，参与这些电位产生的神经元集合位于腰段背角，与低阈值皮肤传入终止的区域相同.在自发性nCDP发生期间，促进了从低阈值皮肤传入到第三-第六层二级神经元的传递，以及沿着皮肤和Ib传入的介导PAD的沿着通路的传递。相反，Ia传入的PD被抑制。单突触反射的屈肌和伸肌促进自发nCDP。促进的幅度与“条件反射”自发nCDP的幅度成比例。这导致自发nCDPs的振幅波动与单突触反射的波动之间存在高度正相关性。刺激低阈值皮肤传入神经可短暂降低自发性nCDPs的发生概率以及单突触反射的波动。可以得出结论，自发nCDPs产生的背角神经元，共享相同的功能通路，并涉及相同的一组神经元的刺激大的皮肤传入的单突触响应的人口的激活。这些神经元的自发活动可能是麻醉下观察到的单突触反射波动的主要原因，并可以提供节段性感觉和运动通路之间的动态联系。
1. We examined, in the anaesthetised cat, the influence of the neuronal ensembles producing spontaneous negative cord dorsum potentials (nCDPs) on segmental pathways mediating primary afferent depolarisation (PAD) of cutaneous and group I muscle afferents and on Ia monosynaptic activation of spinal motoneurones.2. The intraspinal distribution of the field potentials associated with the spontaneous nCDPs indicated that the neuronal ensembles involved in the generation of these potentials were located in the dorsal horn of lumbar segments, in the same region of termination of low-threshold cutaneous afferents.3. During the occurrence of spontaneous nCDPs, transmission from low-threshold cutaneous afferents to second order neurones in laminae III-VI, as well as transmission along pathways mediating PAD of cutaneous and Ib afferents, was facilitated. PD of Ia afferents was instead inhibited.4. Monosynaptic reflexes of flexors and extensors were facilitated during the spontaneous nCDPs. The magnitude of the facilitation was proportional to the amplitude of the 'conditioning' spontaneous nCDPs. This led to a high positive correlation between amplitude fluctuations of spontaneous nCDPs and fluctuations of monosynaptic reflexes.5. Stimulation of low-threshold cutaneous afferents transiently reduced the probability of occurrence of spontaneous nCDPs as well as the fluctuations of monosynaptic reflexes.6. It is concluded that the spontaneous nCDPs were produced by the activation of a population of dorsal horn neurones that shared the same functional pathways and involved the same set of neurones as those responding monosynaptically to stimulation of large cutaneous afferents. The spontaneous activity of these neurones was probably the main cause of the fluctuations of the monosynaptic reflexes observed under anaesthesia and could provide a dynamic linkage between segmental sensory and motor pathway.