Elliott C J, Benjamin P R
J Neurophysiol. 1985 Dec;54(6):1412-21. doi: 10.1152/jn.1985.54.6.1412.
We have used intracellular recording from groups of interneurons in the feeding system of the pond snail, Lymnaea stagnalis, to examine the connections of a modulatory interneuron, the slow oscillator (SO), with the network of pattern-generating interneurons (N1, N2, and N3). The SO is an interneuron whose axon branches solely within the buccal ganglia. There is only one such cell in each snail. In half the snails the cell body is in the right buccal ganglion and in the other half in the left buccal ganglion. Stimulation of either the SO or one of the N1 pattern-generating interneurons elicits the feeding rhythm, but of all the buccal neurons, only the SO can drive the feeding rhythm at the frequency seen in the intact snail. The SO makes reciprocal excitatory synapses with the N1 interneurons that drive the protraction of the radula. This ensures strong activation of the feeding system. The SO inhibits the N2 interneurons. Postsynaptic potentials evoked by stimulation of the SO facilitate without spike broadening in the SO. The SO is strongly inhibited by N2 and N3 interneurons, which are active during the retraction phase. This gates any excitatory inputs to the SO, probably preventing protraction of the radula while retraction is underway. The results support the idea of a single interneuron capable of driving a hierarchically organized motor system.
我们利用细胞内记录法，对椎实螺（Lymnaea stagnalis）摄食系统中的中间神经元群进行记录，以研究一种调节性中间神经元——慢振荡器（SO）与模式生成中间神经元网络（N1、N2和N3）之间的连接。SO是一种中间神经元，其轴突仅在颊神经节内分支。每只蜗牛中只有一个这样的细胞。在一半的蜗牛中，细胞体位于右侧颊神经节，另一半位于左侧颊神经节。刺激SO或N1模式生成中间神经元之一会引发摄食节律，但在所有颊神经元中，只有SO能够以完整蜗牛中所见的频率驱动摄食节律。SO与驱动齿舌前伸的N1中间神经元形成相互兴奋性突触。这确保了摄食系统的强烈激活。SO抑制N2中间神经元。刺激SO诱发的突触后电位在SO中促进而不出现锋电位展宽。SO受到在缩回阶段活跃的N2和N3中间神经元的强烈抑制。这限制了对SO的任何兴奋性输入，可能在缩回进行时阻止齿舌前伸。这些结果支持了单个中间神经元能够驱动分层组织的运动系统这一观点。
