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.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS036447-09
Application #
7389519
Study Section
Cognitive Neuroscience Study Section (COG)
Program Officer
Stewart, Randall R
Project Start
1999-09-15
Project End
2011-01-31
Budget Start
2008-02-01
Budget End
2011-01-31
Support Year
9
Fiscal Year
2008
Total Cost
$272,243
Indirect Cost
Name
Georgetown University
Department
Type
Organized Research Units
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057
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Baker, Bradley; Gao, Xin; Wolff, Brian S et al. (2015) Voltage-Sensitive Dye Imaging of Population Signals in Brain Slices. Cold Spring Harb Protoc 2015:995-9
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Wu, Jian-Young; Xiaoying Huang; Chuan Zhang (2008) Propagating waves of activity in the neocortex: what they are, what they do. Neuroscientist 14:487-502
Arai, Yoshiyasu; Mentis, George Z; Wu, Jiang-Young et al. (2007) Ventrolateral origin of each cycle of rhythmic activity generated by the spinal cord of the chick embryo. PLoS One 2:e417
Lippert, Michael T; Takagaki, Kentaroh; Xu, Weifeng et al. (2007) Methods for voltage-sensitive dye imaging of rat cortical activity with high signal-to-noise ratio. J Neurophysiol 98:502-12
Xu, Weifeng; Huang, Xiaoying; Takagaki, Kentaroh et al. (2007) Compression and reflection of visually evoked cortical waves. Neuron 55:119-29

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