Interaction of Time Scales in Forced Rhythmic Networks of Neurons

现在人们普遍认为，认知功能是由分散在整个大脑中的活动支持的，并且信号是在大脑的参与区域之间传递的。 事实上，有一个积极的研究方向，称为连接组学，试图在多个空间尺度上找到这种连接。然而，仅仅找到哪些区域是相连的是不够的。相反，重要的是确定区域如何以及在什么方向上连接。作为神经计算过程的一部分，信号是如何传递和作用的？为了理解这样的神经计算，有必要了解在目标网络中如何处理空间和时间上的信号输入模式。 这是一个庞大的科学计划，其中数学和建模可以在指导实验中发挥核心作用。本研究的目的是产生一个身体的工作，是在添加具有时序结构的网络表现出节奏结构的输入遇到的一般问题的代表。 从这样的例子中，这个项目的目标是寻找关于外部输入神经元网络的一般原理。这种受迫网络比简单的受迫振子现象复杂得多。该项目将支持两名研究生，并将在认知节律协作的背景下进行，这是一个由波士顿地区的二十多个实验室（大部分）支持的NSF支持的小组，致力于大脑动力学和认知。 CRC旨在促进其许多团体之间的合作，特别关注这些团体的研究生和博士后。 该项目关注具有多个时间尺度的输入信号对也具有多个时间尺度的神经元目标网络的影响。 从这些现象在神经系统中表现出来的大量例子中，这项研究集中在两个特别重要的生物学上。 第一个是伽马和θ节律的相互作用，主要是在海马网络中，来自海马和新皮层其他部分的输入也带有这种时间模式。 第二个问题涉及到一种节律，这种节律已经在体外顶叶皮层的一个区域进行了实验和计算研究;顶叶皮层是已知的连接枢纽，有来自许多其他区域的输入。 所讨论的特定节律作为刺激的后效应而出现，并且已经通过计算显示出改变了网络对稍后的紧张性兴奋的反应。 这项研究将提高对网络的影响的理解，该网络显示具有更复杂光谱特性的输入节奏，例如来自其他大脑区域的输入。所涉及的网络既有兴奋性细胞，也有抑制性细胞，有时在目标网络中产生多个时间尺度的不止一种抑制性细胞。

It is now well accepted that cognitive functions are supported by activity dispersed throughout the brain, and that signals are passed among participating regions of the brain. Indeed, there is an active direction of study, known as connectomics, that seeks to find such connections on multiple spatial scales. It is not sufficient, however, to find what regions are connected. Rather it is important to determine how and in what directions regions are connected. How are signals conveyed and acted upon as part of a neural computational process? To understand such neural computations, it is necessary to understand how input patterns of signals in space and time are processed at the target network. This is a huge scientific program in which mathematics and modeling can play a central role in guiding experiments. The aim of this research is to produce a body of work that is representative of the general issues that are encountered in adding input that has timing structure to networks exhibiting rhythmic structure. From such a body of examples, a goal of this project is to search for general principles about networks of neurons with external input. Such forced networks are far more complex than the well-studied phenomena of simple forced oscillators. This project will support two graduate students and will be carried out within the context of the Cognitive Rhythms Collaborative, a NSF-supported group of more than two dozen labs (mostly) in the Boston area working on brain dynamics and cognition. The CRC is designed to facilitate collaborations among its many groups, with special attention to the graduate students and postdocs of these groups. This project is concerned with the effects of input signals with multiple time scales on target networks of neurons that also have multiple time scales. From the huge number of examples of these phenomena manifest in the nervous system, this research is focused on two of particular biological importance. The first is the interaction of gamma and theta rhythms, mainly in hippocampal networks, with inputs from other parts of the hippocampus and neocortex also carrying such temporal patterns. The second concerns a rhythm that has been experimentally and computationally investigated in a region of parietal cortex in vitro; parietal cortices are known to be hubs of connections, with inputs from many other areas. The particular rhythm in question arises as an after-effect of stimulation, and has been shown computationally to change the network response to later tonic excitation. This research will improve understanding of the effect on a network displaying this rhythm of input with more complex spectral properties, such as inputs from other brain regions. The networks involved have both excitatory and inhibitory cells, sometimes with more than one kind of inhibitory cell producing multiple time scales in the target network.