Implantable biomimetic electronics as a neural prosthesis for lost memory function

Dr. Berger will present results of a collaborative effort on the part of the University of Southern California, Wake Forest University, and the University of Kentucky to develop a nonlinear dynamic model of synaptic transmission in the hippocampus. The model is implemented in very large scale integrated (VLSI) circuitry for use as a neural prosthetic to replace damaged or dysfunctional brain tissue. The hippocampus is a region of the brain responsible for the formation of long-term memories, and frequently is damaged as a result of epilepsy, stroke, and Alzheimer's disease. The components of this multi-laboratory effort will be described, and include: (1) experimental study of neuron and neural network function - how does the hippocampus encode information?, (2) formulation of biologically realistic models of neural system dynamics - can that encoding process be described mathematically to predict how the hippocampus (or a region of the hippocampus) will respond to a particular event?, (3) microchip implementation of neural system models - can the mathematical model be realized as a set of electronic circuits to achieve rapid computational speed and miniaturization?, and (4) hybrid neuron-silicon interfaces - can electronic devices be "functionally connected" to neural tissue for bi-directional communication with the hippocampus?. By integrating solutions to these component problems, the team is realizing a microchip-based model of hippocampal nonlinear dynamics that can perform the same function as a removed, damaged hippocampal region. Through bi-directional communication with other neural tissue that normally provides the inputs and outputs to/from the damaged hippocampal area, the neural model can serve as a neural prosthesis. A proof-of-concept will be presented in which the CA3 region of the hippocampal slice is replaced by a microchip model of CA3 nonlinear dynamics. How the current work in brain slices is being extended to behaving animals also will be described