SYNAPTIC INTEGRATION AND PROPAGATION IN CA1 DENDRITES

中枢神经系统中的每个神经元都有一棵实质性的树枝树 它接收来自大脑上成千上万个突触中的大多数的输入， neuron. 突触输入相互作用，与被动 树突的电结构，并与电压门控通道， 树突、索马和轴突在一个复杂的过程中，通常被称为 突触整合 这些电相互作用，主要发生在 树突树确定在给定时间神经元是否发送 通过动作电位向下传播向其网络伙伴发出信号 轴突 因此，树突在决定 一个神经元在其网络中的功能，但相对而言知之甚少 它们的电性能，部分原因是它们的尺寸小， 使得树突难以记录。 然而最近， 已经开发出允许膜片吸管记录的技术， 通常由脑切片中的神经元树突制成。 的 这里提出的实验利用这种技术，通常使用 同时记录同一个神经元上的两个点，目标是 更好地理解突触整合的过程， 海马锥体神经元树突。 脑组织索马和树突的膜片钳同步记录 海马CA1区锥体神经元显示动作电位是 起源于这些神经元的索马附近。 因此， 我们知道突触电位在传播时有多少衰减， 树突向索马的方向移动，以了解 树突状突触产生动作电位放电。 这 问题将通过直接检查衰减来解决 树突和体细胞记录位点之间的突触电位。 作为 突触电位从树突向索马传播，然而， 它们可能受到树突状电压门控通道的影响， 突触去极化 这些渠道对 因此，将通过检查以下因素的影响来研究EPSP的传播 各种信道阻断剂对"EPSP"传播的影响， 通过树突状斑块的EPSC形状的电流注入 移液管。 此外，为了了解超极化的作用， 对EPSPs从树突到树突的增殖的分流抑制 索马，模拟IPSC的电流注射的效果，或局部 将GABA应用于树突，将进行检查。 连同关于树突状电压门控的作用的信息， 通道和抑制在塑造EPSP传播，详细 海马神经元树突中电压传播的描述 将用于构建真实的房室传播模型， 神经元，应该证明有用的研究人员检查的作用， 这些神经元在神经网络中负责学习过程 和记忆

Each neuron in the central nervous system has a substantial dendritic tree that receives input from the majority of the thousands of synapse on the neuron. Synaptic inputs interact with one another, with the passive electrical structure of the dendrites, and with voltage-gated channels in the dendrites, soma, and axon in a complex process, often referred to as synaptic integration. These electrical interactions, occurring largely in the dendritic tree, determine whether at a given time a neuron sends a signal to its network partners via an action potential propagation down the axon. Dendrites therefore have a prominent role in determining the function of a neuron in its network, yet relatively little is known about their electrical properties, in part due to their small size, which has rendered dendrites difficult to record from. Recently, however, techniques have been developed that allow patch-pipette recordings to be made routinely from the dendrites of neurons in brain slices. The experiments proposed here make use of this technique, often using simultaneous recordings from two points on the same neuron, with the goal of better understanding the process of synaptic integration in the dendrites of hippocampal pyramidal neurons. Simultaneous patch-pipette recordings from the soma and dendrites of hippocampal CA1 pyramidal neurons have revealed that action potentials are initiated near the soma of these neurons. It is therefore critical to know how much synaptic potentials are attenuated as they propagate from the dendrites toward the soma, in order to understand how effective dendritic synapses are at producing action potential firing. This question will be addressed by directly examining the attenuation of synaptic potentials between dendritic and somatic recording sites. As synaptic potentials propagate from the dendrites toward the soma, however, they may be affected by dendritic voltage-gated channels activated by the synaptic depolarization. The contribution of such channels to the propagation of EPSPs will therefore be studied by examining the effects of various channel blockers on the propagation of "EPSPs", simulated by using current injection in the shape of an EPSC through a dendritic patch pipette. Furthermore, to understand the role of hyperpolarization and shunting inhibition on the propagation of EPSPs from the dendrites to the soma, the effects of current injections mimicking IPSCs, or local application of GABA to dendrites, will be examined. Together with information concerning the roles of dendritic voltage-gated channels and inhibition in shaping EPSP propagation, the detailed description of voltage propagation in the dendrites of hippocampal neurons will be used to construct realistic compartmental propagation models of neurons that should prove useful to investigators examining the role of these neurons in neural networks responsible for the processes of learning and memory.