Dynamic Neuronal Organizations in Neocortex

描述（由申请人提供）：本研究的长期目标是了解群体神经元事件（数百万神经元的相关活动）的组织。本研究旨在研究激发波（又称行波）在新皮层中的传播。传播波发生在感觉和运动过程中，也发生在癫痫等神经系统疾病中。控制传播速度和方向的机制对于决定什么样的活动模式将被波携带并在什么时间传递到皮层的哪个部分是很重要的。关于传播方向和速度的控制，我们所知甚少。这是因为脑电波在一个具有平行和多突触通路的分布式神经网络中传播。

DESCRIPTION (provided by applicant): The long-term objective of this study is to understand the organization of population neuronal events (correlated activities of millions of neurons). This proposal studies the propagation of excitation waves (a.k.a. traveling waves) in the neo-cortex. Propagating waves occur during sensory and motor processes as well as during neurological disorders such as epilepsy. The mechanisms that control the propagating velocity and directions are important in determining what kind of activity patterns will be carried by the wave and delivered to what part of the cortex, and at what time. Very little is known about the control of the propagating direction and velocity. This is because the waves travel in a distributed neuronal network with parallel and polysynaptic pathways. This proposal will test a hypothesis that propagating waves are generated by coupled local oscillators. The phase relationship among the local oscillators determines the velocity and direction. Voltage-sensitive dye imaging will be used to visualize the propagation waves generated in vitro, in neo-cortical slices. Three Specific Aims are proposed to study the local oscillators during two kinds of "theta" (4-12 Hz) oscillations and an evoked gamma oscillation. Aim 1 consists of two experiments. One experiment will visualize the local oscillators and the boundaries between them. The other experiment will try to separate individual local oscillators with micro cuts to the cortical tissue. Aim 2 will test the hypothesis on the two-dimensional waves generated in tangential cortical slices. Aim 3 will study the neuronal-composition of an evoked gamma oscillation. The spiking activity of individual neurons will be optically monitored in an attempt to understand how the activities of individual neurons compose a population oscillation. This study will not only contribute to the understanding of normal cortical processing but also to the understanding of the initiation and spreading of epileptic seizure activity in the cortex that disrupts the life of about 1% of the U.S. population.