Antonsen Brian L, Edwards Donald H
Department of Biology, Georgia State University, Atlanta, Georgia 30302-4010, USA.
J Comp Neurol. 2003 Nov 3;466(1):1-13. doi: 10.1002/cne.10802.
The lateral giant (LG) escape circuit of crayfish mediates a coordinated escape triggered by strong attack to the abdomen. The LG circuit is one of the best understood of small systems, but models of the circuit have mostly been limited to simple ball-and-stick representations, which ignore anatomical details of contacts between circuit elements. Many of the these contacts are electrical; here we use differential dye coupling, a technique which could help reveal connection patterns in many neural circuits, to reveal in detail the circuit within the terminal abdominal ganglion. Sensory input from the tailfan forms a somatotopic map on the projecting LG dendrites, which together with interafferent coupling mediates a lateral excitatory network that selectively amplifies strong, phasic, converging input to LG. Mechanosensory interneurons contact LG at sites distinct from the primary afferents and so maximize their summated effect on LG. Motor neurons and premotor interneurons are excited near the initial segments of the LGs and innervate muscles for generating uropod flaring and telson flexion. Previous research has shown that spatial patterns of input are important for signal integration in LG; this map of electrical contact points will help us to understand synaptic processing in this system.
小龙虾的外侧巨（LG）逃逸回路介导由对腹部的强烈攻击触发的协调逃逸。LG回路是小型系统中理解最透彻的回路之一，但该回路的模型大多局限于简单的球棒表示法，这种表示法忽略了回路元件之间接触的解剖学细节。这些接触中有许多是电接触；在这里，我们使用差分染料耦合技术（一种有助于揭示许多神经回路连接模式的技术）来详细揭示末节腹神经节内的回路。来自尾扇的感觉输入在投射的LG树突上形成一个躯体定位图，该图与传入神经元间耦合一起介导一个外侧兴奋性网络，该网络选择性地放大对LG的强烈、相位性、汇聚性输入。机械感觉中间神经元在与初级传入神经元不同的部位与LG接触，从而最大限度地增强它们对LG的总和效应。运动神经元和运动前中间神经元在LG的起始段附近被激活，并支配肌肉以产生尾足展开和尾节弯曲。先前的研究表明，输入的空间模式对LG中的信号整合很重要；这个电接触点图将有助于我们理解该系统中的突触处理。
