NONLINEAR DYNAMICS OF NEURONAL ENSEMBLES

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The PI is a Neurophysiologist and Pediatric Neurosurgeon who will be the Associate Director of Center V (Behavioral and Neurobiology Research), with special responsibility for Neurobiology programs, at the Children"s Research Institute. This RCA will permit the PI to devote nearly full time to research. Short term goals are to test the hypothesis that neuronal ensembles have nonlinear deterministic properties. If so, they will 1) have activity that can be characterized and controlled through unstable periodic orbits, 2) hen noise driven will exhibit stochastic resonance, and 3) because of coupling will exhibit generalized (nonlinear) synchrony and emergence. Long-term goals are to achieve a better understanding of neuronal network and brain behavior, and to develop novel methods of treating dynamical diseases. The research project will involve theoretical work on the detection of unstable orbits in In Vitro brain slices and human epileptic foci. Such orbit information forms a novel method of characterizing the deterministic properties of complex systems despite nonstationarity, and can be used to control those systems. Nonlinear systems also optimize their response to weak signals in the presence of noise - stochastic resonance. We will define the statistical mechanics of stochastic resonance through simultaneous measurements of single neuron and neuronal ensemble activity. Since neuronal ensembles may demonstrate nonlinear generalized synchrony, we will quantify spatio-temporal generalized synchrony through dual simultaneous single cell recordings as a function of separation in a neuronal network. Both unstable orbit detection and generalized synchrony will be used to define the emergence of nonlinear behaviors in neuronal ensembles. The results of this research will fundamentally alter the way that neuronal dynamics can be characterized and controlled, will provide a means to deal with neuronal nonstationarity, will further explain the role of noise in the nervous system, and may provide a novel approach for the control of pathological neuronal ensembles in dynamical diseases such as epilepsy, spasticity, and tremor.