Segmental giant: evidence for a driver neuron interposed between command and motor neurons in the crayfish escape system.
Segmental giant: evidence for a driver neuron interposed between command and motor neurons in the crayfish escape system.
复制标题
节段巨人：小龙虾逃逸系统中命令神经元和运动神经元之间存在驱动神经元的证据。
DOI：
10.1152/jn.1982.47.5.761
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发表时间：
1982
影响因子：
2.5
通讯作者：
Kramer,AP
中科院分区：
文献类型：
--
作者：
Roberts,A;Krasne,FB;Hagiwara,G;Wine,JJ;Kramer,AP
1.研究发现，控制小龙虾甩尾逃逸行为的巨型指令神经元通过单突触连接激活非巨型快屈肌运动神经元。我们在这里表明，相反，通过一个双边对节段性巨神经元（SG）插入之间的命令轴突和FF在每个部分的FF的兴奋发生。2.在解剖学上，SG似乎与同侧的命令轴突和FF进行了大量接触，而对侧的接触较少。相比之下，指挥轴突只有稀疏的直接连接到FF。SG在同侧第一神经节根中具有轴突，并且可能是修饰的游泳神经元。3.每个SG通过同侧命令轴突的发射而被去极化远超过阈值，并且通过对侧命令轴突的发射而被去极化至接近阈值。指挥轴突和SG之间的突触是电的，可能是整流的。4.每个FF被其轴突同侧的SG激发到接近放电阈值的水平，并且被对侧的SG微弱地激发。SG和FF之间的突触是电的和非整流的。5.兴奋性突触后电位（EPSP）的变化记录在FF在长时间，高频率发射的命令轴突可以占不应性的SG尖峰，而不是不应性的树突状分支尖峰，因为以前已经交付。6.这些发现说明了单突触性的传统测试的局限性。7.将驱动神经元插入命令神经元和运动神经元之间的功能意义进行了讨论。
1. The giant command neurons for tailflip escape behavior in crayfish have been thought to excite the nongiant fast flexor (tailflip producing) motor neurons (FFs) via monosynaptic connections. We show here that excitation of FFs instead occurs via a bilateral pair of segmental giant neurons (SGs) interposed between the command axons and FFs in each segment. 2. Anatomically, the SGs appear to make numerous contacts with ipsilateral command axons and FFs and fewer contacts contralaterally. In contrast, the command axons have only sparse direct connections to the FFs. An SG has an axon in the ipsilateral first ganglionic root and may be a modified swimmeret motor neuron. 3. Each SG is depolarized well beyond threshold by the firing of an ipsilateral command axon and is depolarized to near threshold by the firing of a contralateral command axon. The synapses between command axons and SGs are electrical and probably rectifying. 4. Each FF is excited to a level near firing threshold by the SG ipsilateral to its axon and is excited weakly by the contralateral SG. The synapses between SGs and FFs are electrical and nonrectifying. 5. Variations in excitatory postsynaptic potentials (EPSPs) recorded in FFs during prolonged, high-frequency firing of the command axons can be accounted for by refractoriness of SG spikes, as opposed to refractoriness of dendritic branch spikes as had previously been delivered. 6. These findings illustrate the limitations of conventional tests for monosynapticity. 7. The functional significance of having driver neurons interposed between command neurons and motor neurons is discussed.