Mechanisms of Synaptic Integration in Central Neurons

描述（由申请人提供）： 这次Merit Review竞争性更新的拟议实验是许多实验室努力确定中枢神经系统神经元如何编码其突触输入的一部分。特别是，这些实验旨在确定特定神经元（或这些神经元的异常功能）如何有助于在正常信号处理和癫痫发作活动期间发生的同步网络活动。主要的问题是“突触活动的自然模式的哪些时间方面对驱动神经元的动作电位放电最有效？”“和”潜在的机制是什么？“我们专注于新皮层（锥体神经元）中的主细胞对局部回路活动的反应。会聚突触 由皮层网络产生的活动具有类似于随机噪声的宽频谱。我们已经证明，锥体神经元对这种类型的输入表现出共振放电。也就是说，它们的输入驱动器的特定频率分量比其他更好地激发。两个输入频率引起谐振：theta（~7 Hz）和快速涟漪（~300 Hz）。其他研究指出，某些钾传导机制对锥体神经元的共振类型和数量至关重要。已知这些钾通道（Kv 1）之一的基因（KCN 1）突变和针对Kv1.1蛋白的抗体会导致人类中枢神经元的自发和过度放电，导致运动功能问题。我们目前的建议包括三组实验。首先，我们将确定 kv 1通道在树突状细胞对兴奋性输入的过滤中的作用。在第二组中，我们将确定Kv 1通道对树突状细胞输入（例如共振放电）的阈上反应的影响。在第三组中，我们将研究由树突状Kv1.1通道亚基的正常和病理性上调引起的神经元兴奋性的变化。该方法采用贴片移液管记录大脑切片中可视化的神经元。神经元受到树突棘附近笼状谷氨酸的双光子光解的刺激。神经元也在电流钳和动态钳中使用计算机生成的波形来刺激，所述波形模拟到达索马的正在进行的突触活动的统计（主要集中在兴奋性输入上）。为了研究钾通道如何影响反应，在电记录期间将钾通道阻断剂施加于神经元。神经元的解剖学分类通过用荧光染料进行细胞内染色来完成。

DESCRIPTION (provided by applicant): The proposed experiments of this Merit Review competitive renewal are part of the effort by many labs to determine how central nervous system neurons encode their synaptic inputs. In particular, the experiments are designed to determine how specific neurons (or abnormal function of those neurons) contribute to synchronous network activity that occurs both during normal signal processing and during seizure activity. The major questions are 'What temporal aspects of natural patterns of synaptic activity are most effective for driving a neuron's action potential firing?' and 'What are the underlying mechanisms?' We focus on the responses of principal cells in neocortex (pyramidal neurons) to local circuit activity. The convergent synaptic activity generated by cortical networks has a broad frequency spectrum, similar to random noise. We have shown that the pyramidal neurons show resonant firing to this type of input. That is, specific frequency components of their input drive firing better than others. Two input frequencies cause the resonance: theta (~7 Hz) and fast ripple (~300 Hz). Additional studies point to certain potassium conductance mechanisms as being critical for the type and amount of resonance a pyramidal neuron has. A mutation in the gene (KCN1) for one of these potassium channels (Kv1) and antibodies against the Kv1.1 protein are known to cause spontaneous and excessive discharges of central neurons in humans, leading to problems with motor function. Our current proposal includes three sets of experiments. In the first we will determine the role of Kv1 channels in dendritic filtering of excitatory inputs. In the second set we will determine the effect of Kv1 channels on the suprathreshold responses to dendritic inputs (e.g. resonant firing). In the third set we will examine the changes in neuronal excitability caused by normal and pathologic up-regulation of dendritic Kv1.1 channel subunits. The methods employ patch pipettes to record from visualized neurons in brain slices. Neurons are stimulated by 2-photon photolysis of caged glutamate near spines on dendrites. Neurons are also stimulated in current clamp and dynamic clamp using computer-generated waveforms that simulate the statistics of ongoing synaptic activity arriving at the soma (focusing mostly on excitatory inputs). To investigate how potassium channels affect the responses, potassium channel blockers are applied to the neurons during the electrical recording. Anatomical classification of neurons is done by intracellular staining with a fluorescent dye.