HIPPOCAMPAL INHIBITION--CIRCUITRY AND MATURATION

拟议项目的总体目标是进一步推动我们的 对抑制的连通性和成熟性的理解 海马体中的回路。直到最近，人们还认为 海马区抑制的激活依赖于 谷氨酸介导的兴奋，通过前馈和反馈途径。 我们最近的研究表明，抑制性中间神经元可以 也可以通过两条不需要谷氨酸的途径招募- 介导的神经传递：(1)通过GABA的去极化作用 突触连接中间神经元的BABA/A受体的研究(2) 通过假定的电子紧张性耦合。拟议的研究将进一步 描述这些不依赖谷氨酸的新型抑制物 同步进程。大鼠海马区的体外实验 将进行切片以解决三个主要问题。这些是(1) 证实了一个亚群之间的电紧性耦合 中间神经元，(2)中间神经元形态分析以确定 细胞功能分化的结构相关因素 中间神经元分成不同亚群和(3)测定 这些谷氨酸非依赖性同步化的发育概况 在未成熟的大脑中的过程。所有的实验都将涉及 识别出的抑制性神经元的细胞内记录，在大多数情况下 2例为CA3锥体细胞。将验证电子紧张性耦合 直接使用配对录音，并收集支持性数据 使用细胞内的染料标记来揭示染料偶联细胞， 挥发性麻醉药的应用及其改进 细胞外环境(两种程序都旨在破坏GAP 交叉点)。将进行中间神经元的形态分析 使用细胞内标记神经生物素，同时 电生理分析的内在属性，突触和 电紧性耦合。发展研究将评估 中间神经元的内源性成熟与神经细胞的成熟 抑制回路作为一个整体，与其输出到锥体上有关 细胞。 抑制回路在正常功能中起着不可或缺的作用 在海马体中，并且对于限制海马体的传播至关重要 在癫痫等情况下的异常活动。我们最近的研究 证明了抑制电路要比 之前意识到的。拟议研究中的实验将 研究这一复杂性，以便我们能够进一步了解 海马区正常和异常的网络功能。

The overall objective of the proposed project is to further our understanding of the connectivity and maturation of the inhibitory circuit in the hippocampus. Until recently, it was believed that the activation of inhibition in the hippocampus was dependent upon glutamate-mediated excitation, via feedforward and feedback pathways. Our recent studies have demonstrated that inhibitory interneurons can also be recruited through two pathways which do not require glutamate- mediated neurotransmission: (1) via the depolarizing action of GABA on BABA/A receptors from synaptically connected interneurons and (2) via presumed electrotonic coupling. The proposed study will further characterize these novel, glutamate-independent inhibitory synchronization processes. In vitro experiments on the hippocampal slice will be performed to address three major issues. These are (1) confirmation of electrotonic coupling among a subpopulation of interneurons, (2) analysis of interneuron morphology to determine structural correlates for the functional differentiation of interneurons into various subgroups and (3) determination of the developmental profile of these glutamate-independent synchronization processes in the immature brain. All experiments will involve intracellular recording from identified inhibitory neurons and, in most cases, CA3 pyramidal cells. Electrotonic coupling will be verified directly, using paired recordings, and supportive data will be gathered using intracellular dye markers to uncover dye-coupled cells, application of volatile anesthetics and modification of the extracellular milieu (both procedures designed to disrupt gap junctions). Morphological analysis of interneurons will be performed using the intracellular marker Neurobiotin, with simultaneous electrophysiological analyses of intrinsic properties, synaptic and electrotonic coupling. The developmental studies will assess both the intrinsic maturation of interneurons and the maturation of the inhibitory circuit as a whole, as related to its output onto pyramidal cells. The inhibitory circuit plays an integral role in the normal function of the hippocampus, and is essential for limiting the propagation of abnormal activity in conditions such as epilepsy. Our recent studies demonstrate that the inhibitory circuit is much more complex than previously realized. The experiments in the proposed study will examine this complexity so that we can further our understanding of the normal and abnormal network function in the hippocampus.