Role of Field Effects in Coherent Hippocampal Oscillations

几种大脑行为、认知或知觉状态与时间上准确的神经元有关 开火。理解这种准确性的来源，尽管有很大的噪音，仍然是一个 脑研究中的基本问题。已经表明，时间精度可以通过以下方式实现 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 胞外场电势和通过‘场效应相互作用’，这些胞外电势将 一致地使神经元群体极化。该项目提出并将通过以下方式测试两种新机制 这种小电场的效应在单个神经元水平上被显著放大，并在 网络水平：1)体细胞膜电位的微小极化可以显著影响穗的计时； 大量神经元的棘波时序的相干变化可以深刻地影响网络动力学 和同步性。我们假设在海马区，内源性细胞外电位 连贯地极化神经元群体，从而提高网络峰电位计时的准确性。这 该项目旨在量化自然产生的“内源性”胞外场与 神经元网络中的尖峰时间一致性。具体地说，小的非均匀场将应用于 海马片定量研究细胞外场对神经细胞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脉冲的递归网络模型中 神经元验证场效应在调制相干峰电位中的作用 伽马和西塔振荡。这种方法将实验与建模紧密地联系在一起 研究人员在电生理学和场效应(Bikson)和信号处理/神经元方面的专业知识 网络建模(PARRA)。我们关于小场放大的结果同样适用于环境电学 神经假体脑刺激器(例如DBS)所产生的电场(例如电力线)和电场，因此 提出了一种考虑低幅度电场影响的新框架。 我们的大脑暴露在由大脑本身和环境产生的电场中。这 该项目将演示大脑是如何放大这些电场的，从而使之前的电场 考虑到太小，这可能与正常的大脑功能和疾病相关。

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.