Serial-section atlas of the Tritonia pedal ganglion

The pedal ganglion of the nudibranch gastropod Tritonia diomedea has been the focus of neurophysiological studies for more than 50 years. These investigations have examined the neural basis of behaviors as diverse as swimming, crawling, reflex withdrawals, orientation to water flow, orientation to the earth’s magnetic field, and learning. In spite of this sustained research focus, most studies have confined themselves to the layer of neurons that are visible on the ganglion’s surface, leaving many neurons, which reside in deeper layers, largely unknown and thus unstudied. To facilitate work on such neurons, the present study used serial section light microscopy to generate a detailed pictorial atlas of the pedal ganglion. One pedal ganglion was sectioned horizontally at 2 µm, and another vertically at 5 µm intervals. The resulting images were examined separately or combined into stacks to generate movie tours through the ganglion. These were also used to generate 3D reconstructions of individual neurons, and rotating movies of digitally desheathed whole ganglia to reveal all surface neurons. A complete neuron count of the horizontally sectioned ganglion yielded 1885 neurons. Real and virtual sections from the image stacks were used to reveal the morphology of individual neurons, as well as the major axon bundles traveling within the ganglion to and between its several nerves and connectives. Extensive supplemental data are provided, as well as a link to the Dryad Data Repository site where the complete sets of high resolution serial section images can be downloaded.

裸鳃类腹足动物（nudibranch gastropod）Tritonia diomedea的足神经节（pedal ganglion）已成为神经生理学研究的核心对象，相关研究已开展五十余年。此类研究系统解析了游泳、爬行、反射退缩、水流定向、地磁场定向以及学习等多种行为的神经基础。尽管该领域长期受到持续关注，但绝大多数研究仅局限于神经节表面可见的神经元层，导致大量深藏于神经节深层的神经元几乎未被探明，相关研究亦长期处于空白。为推动此类深层神经元的相关研究，本研究采用连续切片光学显微镜技术（serial section light microscopy），构建了该足神经节的详细图像图谱。研究人员对一枚足神经节进行2微米间距的水平连续切片，对另一枚进行5微米间距的垂直连续切片。所得图像既可单独分析，也可组合为图像堆栈以生成贯穿神经节的动态漫游视频。此外，这些图像还可用于构建单个神经元的三维重建模型，以及对数字化脱鞘的完整神经节制作旋转视频，以完整展示所有表面神经元。对该水平切片神经节的完整神经元计数结果为1885个。图像堆栈中的真实切片与虚拟切片，可用于解析单个神经元的形态结构，以及在神经节内往返于其多条神经与连接索之间的主要轴突束。本研究附带大量补充数据，并提供了Dryad数据仓储（Dryad Data Repository）的链接，用户可在此下载全套高分辨率连续切片图像。