"Everything should be made as simple as possible, but not simpler." - Albert Einstein

Seminar Announcement

Nonlinear Modeling of Neural Population Dynamics for Hippocampal Prostheses

Dong Song, University of Southern California

Monday, March 29, 2010

4:00 p.m., Weber 223

Developing a neural prosthesis for the damaged hippocampus requires restoring the transformation of population neural activities performed by the hippocampal circuitry.  To bypass a damaged region, output spike trains need to be predicted from the input spike trains and then reinstated through stimulation.  We formulate a multiple-input, multiple-output (MIMO) nonlinear dynamic model for the input-output transformation of spike trains.  In this approach, a MIMO model is comprised of a series of physiologically-plausible multiple-input, single-output (MISO) neuron models that each consists of five components: (1) feed forward Volterra kernels transforming the input spike trains into the synaptic potential, (2) a feedback kernel transforming the output spikes into the spike-triggered after-potential, (3) a noise term capturing the system uncertainty, (4) an adder generating the pre-threshold potential, and (5) a threshold function generating output spikes.  It is shown that this model is equivalent to a generalized linear model with a probit link function.  To reduce model complexity and avoid overfitting, statistical model selection and cross-validation methods are employed to choose the significant inputs and interactions between inputs.  The model is applied successfully to the hippocampal CA3-CA1 population dynamics.  Such model can serve as the computational basis of the development of hippocampal prostheses.