STUDIES OF SMALL NETWORKS OF NEURONS

本研究的目的是探讨小网络的属性 突触连接的哺乳动物神经元，在微培养中形成， 大约10个细胞。 这些网络的发展将是 观察到，并将进行研究，以揭示系统的模式， 连通性。 随后，长期强加的模式的影响， 将研究网络上的活动，以及 切除一个或多个细胞。 该实验室开发的一种系统将用于非侵入性地 从微培养物中刺激和记录，以确定突触 在特定时间的连接，然后对于相同的微培养， 以后的时间。 该系统，这是现在使用，采用电压敏感 用于记录的染料和用于刺激的微电路培养皿。 的 培养皿包含61个细胞外刺激物的阵列 微培养物覆盖的小区域下的电极。 与这些 电极，可以刺激任何细胞，并且可以施加刺激。 随着文化的发展， 对所有刺激的反应 培养物中的细胞可以在染料的帮助下同时测量， 其检测细胞膜电位的变化。 拟议的调查旨在阐明基本原则， 网络中神经元之间的连通性和可塑性。 起初， 由交感神经元形成的简单的纯兴奋性网络将是 研究了 之后，将检查CNS神经元的复杂培养物。 在这些实验中，将测量对突触的影响。 一对突触前和突触后神经元同时兴奋强度 小区，通常被假设为用于网络自适应的方法， 学习 此外，将进行实验以评估 当两个突触前神经元在一个共同的突触后竞争时， cell. 这些研究以及其他各种研究将利用 非侵入性系统提供的独特机会， 活动对蜂窝和网络特性的影响。

The aim of this research is to investigate the attributes of small networks of synaptically connected mammalian neurons, formed in microcultures of approximately 10 cells. The development of these networks will be observed, and studies will be made to uncover systematic patterns of connectivity. Subsequently, the effects of chronically imposed patterns of activity on the networks will be studied, as well as the effects of ablation of one or more cells. A system developed in this laboratory will be employed to noninvasively stimulate and record from a microculture so as to determine the synaptic connectivity at a particular time, and then for the same microculture at later times. This system, which is now in use, employs a voltage-sensitive dye for recording and microcircuit culture dishes for stimulation. The culture dishes incorporate an array of 61 extracellular stimulating electrodes under the small area covered by a microculture. With these electrodes, any cell may be stimulated, and the stimulation may be applied chronically while the culture grows. The response to a stimulus of all the cells in a culture can be simultaneously measured with the aid of the dye, which detects changes in cell membrane potentials. The proposed investigation is designed to elucidate basic principles of connectivity and plasticity among the neurons in a network. Initially, simple purely excitatory networks formed by sympathetic neurons will be studied. Afterward, complex cultures of CNS neurons will be examined. Among the experiments will be measurements of the effect on synaptic strength of simultaneous excitation of a pair of pre- and postsynaptic cells, often hypothesized to be a method for network adaptation or learning. Also, experiments will be performed to assess the role of activity when two presynaptic neurons compete at a common postsynaptic cell. These studies, as well as a variety of others, will capitalize on the unique opportunities afforded by the noninvasive system for studying the effects of activity on both cellular and network properties.