Neural Mechanisms for Generating Temporal Coding

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Bose9973230 The goal of this project is to develop biophysical modelsand the accompanying mathematical techniques to describe thegeneration of temporal codes by the activity patterns of networksof neurons. The investigators focus on a robust temporal code,called phase precession, that has been experimentally found inthe firing pattern of pyramidal cells in the hippocampus offreely moving rats. This temporal code is believed to signal theanimal's location in a known environment. The investigators applya modeling approach consisting of three complementary methods:mathematical analysis of networks of simplified neurons,simulations of networks of biophysical neurons, and functionalmodeling that incorporates and interprets experimental recordingsfrom freely moving rats. The mathematical approach, usinggeometric singular perturbation theory, exploits the multipletime scales inherent in the intrinsic descriptions of the cellsand the synapses between these cells. Simulations are performedon networks of conductance based neurons. Genetic algorithms,previously developed by the researchers, and bifurcationcontinuation programs aid in analyzing the simulation results. Agoal of the analysis and simulations is to make experimentallyverifiable predictions. The hippocampus is a primary target for epilepsy andAlzheimer's Disease and has a well established role in memoryfunction and in spatial navigation abilities. The dynamicalinteraction between neurons in the hippocampus may be describedusing temporal coding schemes. In order to detect potentiallypathological dynamics of these neurons, it is essential to firstunderstand how these coding schemes are constructed under normalcircumstances. More generally, a fundamental goal of neuroscienceis to understand function from the single neuron level to thesystems level. The objective of this project is to bridge all ofthe levels of detail for one specific system, the hippocampus.This work will also lay the mathematical foundation for researchin other areas of the brain where temporal codes exist. Fundingfor the project is provided by the program of ComputationalMathematics and the Office of Multidisciplinary Activities in MPSand by the Computational Neuroscience program in BIO.