Role of Field Effects in Coherent Hippocampal Oscillations

几种大脑行为、认知或感知状态与时间上准确的神经元信号相关。 击发了解这种精度的来源，尽管存在显著的噪音，仍然是一个问题。 大脑研究的基本问题。它已被证明，时间精度可以实现，通过 同步突触神经元驱动。我们注意到，同步神经元活动也会产生 胞外场电位和通过“场效应相互作用”，这些胞外电位将 连贯地连接一个神经元群体。该项目提出并将测试两种新的机制， 小电场的作用在单个神经元水平上被显著放大， 网络水平：1）体细胞膜电位的小极化可显著影响发放时间; 大量神经元的尖峰时间的一致变化可以深刻地影响网络动力学 和同步。我们假设，在海马，内源性细胞外电位， 相干地对神经元群体进行建模，从而提高网络尖峰定时的准确性。这 该项目旨在量化自然发生的“内源性”胞外场与 神经元网络中的尖峰时间相干性具体而言，将应用小的非均匀场， 海马脑片，以量化细胞外场对神经元膜电位和峰电位的影响 锥体神经元的计时。这些结果将被整合到一个循环网络模型的尖峰 神经元，以证明场效应在调制相干尖峰脉冲中的作用， 伽马和θ振荡。这种方法通过将 研究人员在电生理学和场效应（Bikson）和信号处理/神经元 网络建模（Parra）。我们的小场放大的结果同样适用于环境电 场（例如电源线）和神经假体脑刺激器（例如DBS）诱导的电场， 代表了一个新的框架，考虑低幅度电场的影响。 PH：我们的大脑暴露在由大脑本身和环境产生的电场中。这 该项目将展示大脑如何能够“放大1这些领域，使电场以前 认为太小可能与正常脑功能和疾病有关。

Several brain behavioral, cognitive, or perceptual states are associated with temporally accurate neuronal firing. Understanding the source of this accuracy, which occurs despite significant noise, remain a fundamental problem in brain research. It has been shown that temporal accuracy can be achieved through synchronous synaptic neuronal drive. We note that synchronous neuronal activity also generates extracellular field potentials and that through 'field effect interactions' and these extracellular potentials will coherently polarize a neuronal population. This project proposes and will test two novel mechanisms by which the effect of small electric fields are dramatically amplified at the single neuron level and again at the network level: 1) A small polarization of somatic membrane potential can significantly affect spike timing; 2) A coherent change in spike timing for a large number of neurons can profoundly affect network dynamics and synchronization. We hypothesize that in the hippocampus, endogenous extracellular potentials coherently polarize a neuronal population thereby increasing the accuracy of network spike timing. This project aims to quantify the relationship between naturally occurring 'endogenous' extracellular fields and spike time coherence in neuronal networks. Specifically, small non-uniform fields will be applied to hippocampal slices to quantify the effect of extracellular fields on neuronal membrane potential and spike timing of pyramidal neurons. These results will be integrated into a recurrent network model of spiking neurons to demonstrate the role of field effects in modulating coherent spiking focusing specifically on gamma and theta oscillations. This approach tightly links experimentation with modeling by combining the investigators expertise in electrophysiology and field effects (Bikson), and signal processing/neuronal network modeling (Parra). Our results on small field amplification are equally valid for environmental electric fields (e.g. power lines) and electric fields induced by neuro-prosthetic brain stimulators (e.g. DBS) and thus represent a novel framework for consideration of the effects of low amplitude electric fields. PH: Our brains are exposed to electric fields generated both by the brain itself and by the environment. This project will demonstrate how the brain can 'amplify1 these fields such that electric fields previously considered too small may this be relevant for normal brain function and for disease.