Seichter Henriette A, Blumenthal Felix, Smarandache-Wellmann Carmen R
Emmy Noether Group, Institute of Zoology, University of Cologne.
Emmy Noether Group, Institute of Zoology, University of Cologne;
J Vis Exp. 2014 Nov 25(93):e52109. doi: 10.3791/52109.
Here we demonstrate the dissection of the crayfish abdominal nerve cord. The preparation comprises the last two thoracic ganglia (T4, T5) and the chain of abdominal ganglia (A1 to A6). This chain of ganglia includes the part of the central nervous system (CNS) that drives coordinated locomotion of the pleopods (swimmerets): the swimmeret system. It is known for over five decades that in crayfish each swimmeret is driven by its own independent pattern generating kernel that generates rhythmic alternating activity . The motor neurons innervating the musculature of each swimmeret comprise two anatomically and functionally distinct populations. One is responsible for the retraction (power stroke, PS) of the swimmeret. The other drives the protraction (return stroke, RS) of the swimmeret. Motor neurons of the swimmeret system are able to produce spontaneously a fictive motor pattern, which is identical to the pattern recorded in vivo. The aim of this report is to introduce an interesting and convenient model system for studying rhythm generating networks and coordination of independent microcircuits for students' practical laboratory courses. The protocol provided includes step-by-step instructions for the dissection of the crayfish's abdominal nerve cord, pinning of the isolated chain of ganglia, desheathing the ganglia and recording the swimmerets fictive motor pattern extracellularly from the isolated nervous system. Additionally, we can monitor the activity of swimmeret neurons recorded intracellularly from dendrites. Here we also describe briefly these techniques and provide some examples. Furthermore, the morphology of swimmeret neurons can be assessed using various staining techniques. Here we provide examples of intracellular (by iontophoresis) dye filled neurons and backfills of pools of swimmeret motor neurons. In our lab we use this preparation to study basic functions of fictive locomotion, the effect of sensory feedback on the activity of the CNS, and coordination between microcircuits on a cellular level.
在此，我们展示小龙虾腹神经索的解剖过程。该标本包含最后两个胸神经节（T4、T5）以及腹神经节链（A1至A6）。这条神经节链包含中枢神经系统（CNS）中驱动腹足（游泳足）协调运动的部分：游泳足系统。五十多年来人们已知，在小龙虾中，每个游泳足由其自身独立的模式生成核心驱动，该核心产生有节奏的交替活动。支配每个游泳足肌肉组织的运动神经元包括两个在解剖学和功能上不同的群体。一个负责游泳足的收缩（动力冲程，PS）。另一个驱动游泳足的伸展（返回冲程，RS）。游泳足系统的运动神经元能够自发产生一种虚拟运动模式，该模式与在体内记录的模式相同。本报告的目的是为学生的实践实验室课程引入一个用于研究节律生成网络和独立微电路协调的有趣且便捷的模型系统。所提供的方案包括小龙虾腹神经索解剖、分离神经节链的固定、神经节去鞘以及从分离的神经系统细胞外记录游泳足虚拟运动模式的分步说明。此外，我们可以监测从树突进行细胞内记录的游泳足神经元的活动。在此，我们还简要描述这些技术并提供一些示例。此外，可使用各种染色技术评估游泳足神经元的形态。在此，我们提供细胞内（通过离子电渗法）染料填充神经元以及游泳足运动神经元池逆向填充的示例。在我们实验室，我们使用这个标本研究虚拟运动的基本功能、感觉反馈对中枢神经系统活动的影响以及细胞水平上微电路之间的协调。
