INTEGRATION IN DESCENDING MOTOR PATHWAYS CONTROLLING THE FORELIMB IN THE CAT .12. INTERNEURONES WHICH MAY MEDIATE DESCENDING FEEDFORWARD INHIBITION AND FEEDBACK INHIBITION FROM THE FORELIMB TO C3-C4 PROPRIOSPINAL NEURONS
INTEGRATION IN DESCENDING MOTOR PATHWAYS CONTROLLING THE FORELIMB IN THE CAT .12. INTERNEURONES WHICH MAY MEDIATE DESCENDING FEEDFORWARD INHIBITION AND FEEDBACK INHIBITION FROM THE FORELIMB TO C3-C4 PROPRIOSPINAL NEURONS
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DOI：
10.1007/bf00236286
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发表时间：
1984-01-01
影响因子：
2
通讯作者：
SASAKI, S
中科院分区：
文献类型：
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作者：
ALSTERMARK, B;LUNDBERG, A;SASAKI, S
对C3-C4节段的细胞进行细胞外和细胞内记录，目的是找到前肢可能分别介导下行前馈抑制和反馈抑制的C3-C4固有脊髓神经元[PN]的抑制通路的中间神经元。外侧中间神经元分布于第VII层外侧，分布于C3-C4PN之间，与它们一样，它们从皮质、红核、顶盖和网状脊髓束接受汇聚的单突触EPSP[兴奋性突触后电位]和双突触[抑制性突触后电位]。双突触的IPSP，但很少有单突触的EPSP，由前肢神经诱发。外侧中间神经元不投射到外侧网状核(LRN)。内侧中间神经元位于第V层和第VI层的内侧，位于前肢神经抽动诱发细胞外单突触局部电位的区域。从前肢到这一区域的投射有体位组织。许多神经元从I组肌肉或/和皮肤前肢传入强烈地单突触兴奋。在皮肤传入和高阈值肌肉传入的许多细胞中诱发迟发放电。皮质脊髓抽动在这些细胞中的绝大多数引起单突触兴奋，通常也在EPSP或IPSP晚期引起。典型的红核脊髓和顶盖脊髓扭转既不像皮质脊髓纤维那样引起单突触兴奋，也不像皮质脊髓纤维那样引起迟发效应。在一些中间神经元中，IPSP由前肢神经诱发。约20%的内侧中间神经元向上投射至尾侧脑干。逆行刺激的阈值图显示终止于主要楔核、外楔核和/或LRN，并有一个分支投射到脑内更多的吻侧水平。内侧区有少数神经元向前肢节段投射PN。内侧型和外侧型中间神经元均有抑制作用，并投射到C3-C4PN。前者插入到C3-C4PN的下行前馈抑制通路中，后者插入从前肢到这些PN的反馈抑制通路中。讨论了前馈和反馈抑制通过C3-C4PN从大脑传递到前肢运动神经元的作用。
Extra- and intracellular recording was made from cells in the [cervical] C3-C4 segments with the aim of finding interneurons of previously described inhibitory pathways to the C3-C4 propriospinal neurons [PN] which may mediate descending feed-forward inhibition and feedback inhibition from the forelimb, respectively. The lateral interneurons were found in the lateral part of lamina VII interspersed among the C3-C4 PN and like them they receive convergent monosynaptic EPSP [excitatory postsynaptic potential] and disynaptic IPSP [inhibitory postsynaptic potential] from the cortico-, rubro-, tecto- and reticulospinal tracts. Disynaptic IPSP, but only rarely monosynaptic EPSP, are evoked in them from forelimb nerves. The lateral interneurons do not project to the lateral reticular nucleus (LRN). The medial interneurons were found medially in laminae V and VI in a region where volleys in forelimb nerves evoke extracellular monosynaptic focal potentials. There is somatotopic organization of the projection from the forelimb to this region. Many neurons are strongly monosynaptically excited from group I muscle or/and cutaneous forelimb afferents. Late discharges are evoked in many cells from cutaneous afferents and high threshold muscle afferents. Corticospinal volleys evoked monosynaptic excitation in the great majority of these cells and usually also late EPSP or IPSP. Typically, rubrospinal and tectospinal volleys evoked neither monosynaptic excitation nor late effects as those elicited from corticospinal fibers. In some of the interneurons, IPSP were evoked from forelimb nerves. About 20% of the medial interneurons have an ascending projection to the caudal brain stem. Threshold mapping for antidromic stimulation revealed termination in the main cuneate nucleus, the external cuneate nucleus and/or the LRN and also a branch projecting to more rostral levels in the brain. A few of the neurons in the medial region are PN projecting to the forelimb segments. Interneurons both of the lateral and medial type are inhibitory and project to the C3-C4 PN. The former are intercalated in the descending feed-forward inhibitory pathway to the C3-C4 PN and the latter in the feedback inhibitory pathway from the forelimb to these PN. The role of feed-forward and feedback inhibition of transmission from the brain to forelimb motoneurons via the C3-C4 PN is discussed.