INPUT/OUTPUT PROPERTIES OF MAPPED SENSORY SYSTEMS

这项研究的总体目标是确定神经元如何在一个 相对复杂的、地形映射的感觉系统提取物 并将信息编码到它们尖峰中 列车 研究的具体目的是：1）确定 感觉刺激的参数被编码在 感觉受体和投射中间神经元在这个系统中; 2）， 确定信息编码的准确性; 3） 确定信息如何被编码在 尖峰序列模式; 4）检查机制， 观察到的编码方案实际上是在这个神经内实现的 网络，5）以确定在何种程度上，观察到的准确性 接近理论上的最大极限，考虑到所施加的约束， 通过刺激环境的“物理学”，以及6）检查 通过这些原则优化了系统的功能， 满足这些限制。 所研究的制剂是小鼠的尾部感觉系统。 板球。 该系统对低速的检测和分析起到了中介作用 动物周围环境中的气流 所有相关感官 信息仅由十对初级中心传送到更高的中心， 感觉中间神经元 所有这些输出单元都被标识，并且所有 将与细胞外电极同时监测。 上述前三个目标将通过实施 几种类型的电生理输入/输出分析，主要是 在系统层面上。 信息论的原理将应用于 数据，以获得定量的，独立于模型的测量量 信息编码在感觉受体的尖峰序列中， 初级感觉中间神经元 第四个目标将通过 进一步的电生理测量，其结果将是 体现在基于生理学的系统模型中。 该车型将 在信息论的基础上， 类似于在真实的系统上进行的分析。 第五个目标将通过计算约束来实现 对系统性能的影响 环境 第六个目标将通过计算机实现 机械感受器和中间神经元特性的模拟。 这些研究将阐明与最佳信号相关的一般原则 在感觉系统内的处理，并可能建议通用算法， 通过神经元的集合有效地编码信息。

The overall goal of this research is to determine how the neurons in a relatively complex, topographically-mapped sensory system extract information about stimuli and encode that information in their spike trains. The specific aims of the studies are: 1) to determine what parameters of sensory stimuli are encoded in the spike trains of the sensory receptors and projecting interneurons in this system; 2) to determine the accuracy with which that information is encoded; 3) to determine how the information is encoded within different aspects of the spike train patterns; 4) to examine the mechanisms through which the observed coding scheme is actually implemented within this neural network, 5) to determine the extent to which the observed accuracy approaches the theoretical maximum limits, given the constraints imposed by the "physics" of the stimulus environment, and 6) to examine the principles through which features of the system have been optimized to meet those constraints. The preparation to be studied is the cercal sensory system of the cricket. This system mediates the detection and analysis of low velocity air currents in the animal's immediate environment. All relevant sensory information is carried to higher centers by only ten pairs of primary sensory interneurons. All of these output units are identified, and all will be monitored simultaneously with extracellular electrodes. The first three goals listed above will be achieved by carrying out several types of electrophysiological input/output analyses, primarily at a systems level. Principles of information theory will be applied to the data to obtain quantitative, model-independent measures of the amount of information encoded within the spike trains of sensory receptors and primary sensory interneurons. The fourth goal will be achieved through further electrophysiological measurements, the results of which will be embodied in a physiology-based model of the system. The model will be refined, and its validity tested, on the basis of information theoretic analyses similar to the ones that were carried out on the real system. The fifth goal will be achieved through calculations of the constraints on the system's performance imposed by thermal noise in the air current environment. The sixth goal will be achieved through computer simulations of mechanoreceptor and interneuron characteristics. The studies will elucidate general principles related to optimal signal processing within sensory systems and may suggest general algorithms for efficient coding of information by ensembles of neurons.