INPUT/OUTPUT PROPERTIES OF A MAPPED SENSORY SYSTEM

这个研究项目的目标是确定一个相对的 复杂的感官系统提取和编码来自 外部刺激。系统的响应属性为 在两个水平上观察和表征：在受体水平上 以及在输出层到更高的中枢神经系统水平。在某些时候 实验中，输出中所有细胞的响应 将同时对各层进行监控。对这些数据的分析将 提供输入/输出属性的完整说明和 本系统的编码算法。 拟研究的制剂为颈椎感觉系统。 板球，Acheta home ticus。蟋蟀(和许多其他昆虫) 它们的腹部后部有两个天线状的附属物， 覆盖着成百上千的丝状毛发，就像一根 瓶刷。这些丝状毛发在风流中的偏转 激活机械感受器，该感受器投射到 腹神经节终末形成地形图 (或“地图”)的“风空间”。初级感觉中间神经元具有 这张风空间传入图中的树突分支是 被风的刺激用“相关”参数选择性地激活， 并产生动作电位的频率取决于 这些参数的值。“相关”参数是 被认为是风的方向、速度和加速 直指动物的电流。只有十双这样的 中微子将系统的输出带到更高的中心。 所有这十个输出单元都已确定，并且都将 同时用细胞外电极监测。这个 将解决以下具体问题：什么是 TH感觉受体的反应特性，以及I/O是什么 感受器层作为一个整体的特性？什么是 输出层中所有单元的响应属性？是所有的 方向、速度和加速度信息，即 在接受层提取的也可以在输出层获得吗？ 这些信息是如何编码的？是不是还有更高的等级 “特征”也被编码了吗？敏感度的总体门槛是多少？ 以及整个系统的动态范围进行检测 风刺激的特征？将尝试评估如何 所有观察到的属性都与输出的结构有关 神经元，输出中间神经元的突触连接性 其他局部中间神经元，以及 风图中带有感觉传入的输出神经元 太空。

The goal of this research project is to determine how a relatively complex sensory system extracts and encodes information from external stimuli. The response properties of the system will be observed and characterized at two levels: at the receptor level and at the output layer to higher CNS levels. During some experiments, the responses from all of the cells in the output layer will be monitored simultaneously. Analysis of this data will provide a complete description of the input/output properties and encoding algorithm of this system. The preparation to be studied is the cercal sensory system of the cricket, Acheta domesticus. Crickets (and many other insects) have two antenna-like appendages at the rear of their abdomen, covered with hundreds of "filiform" hairs, resembling bristles on a bottle brush. Deflection of these filiform hairs by wind currents activates mechanosensory receptors, which project into the terminal abdominal ganglion to form a topographic representation (or "map") of "wind space". Primary sensory interneurons having dendritic branches within this afferent map of wind space are selectively activated by wind stimuli with "relevant" parameters, and generate action potentials at frequencies that depend upon the value of those parameters. The "relevant" parameters are thought to be the direction, velocity, and acceleration of wind currents directed at the animal. There are only ten pairs of these interneuons which carry the system's output to higher centers. All ten of these output units are identified, and all will be monitored simultaneously with extracellular electrodes. The following specific questions will be addressed: What are the response properties of th sensory receptors, and what are the I/O properties of the receptor layer as a whole? What are the response properties of all the units in the output layer? Is all of the direction, velocity and acceleration information that is extracted at the receptor layer also available at the output layer? How is that information encoded? Are any higher order "features" also encoded? What is the overall threshold, sensitivity and dynamic range of the system as a whole for detecting features of wind stimuli? An attempt will be made to assess how all of the observed properties relate to the structure of the output neurons, the synaptic connectivity of the output interneurons with other local interneurons, and the synaptic connectivity of the output neurons with the sensory afferents in the map of wind space.