Mechanisms of Synaptic Integration in Central Neurons

描述(由申请人提供)： 这项价值评估竞争性更新的拟议实验是许多实验室确定中枢神经系统神经元如何编码其突触输入的努力的一部分。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)如何促进在正常信号处理和癫痫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？’我们重点研究新皮质(锥体神经元)中的主细胞对局部回路活动的反应。会聚突触 大脑皮层网络产生的活动具有广泛的频谱，类似于随机噪声。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，他们输入驱动的特定频率分量比其他组件激发得更好。有两个输入频率引起谐振：Theta(~7 Hz)和快速纹波(~300 Hz)。其他研究指出，某些钾电导机制对锥体神经元的共振类型和数量至关重要。已知其中一种钾通道(KV1)的基因突变(KCN1)和针对Kv1.1蛋白的抗体会导致人类中枢神经元自发和过度放电，导致运动功能问题。我们目前的建议包括三套实验。在第一部分中，我们将确定 兴奋性输入的树突过滤中的KV1通道。在第二组中，我们将确定KV1通道对树突输入(如共振激发)的阈值上反应的影响。在第三组中，我们将研究树突状Kv1.1通道亚单位正常和病理性上调引起的神经元兴奋性的变化。这种方法使用贴片吸管记录大脑切片中可视化的神经元。树突上棘突附近笼子内谷氨酸的双光子光解刺激神经元。神经元也在电流钳和动态钳中被刺激，使用计算机产生的波形来模拟到达胞体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，在电记录过程中对神经元应用钾通道阻滞剂。神经元的解剖分类是通过用荧光染料进行细胞内染色来完成的。

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.