Design and implementation of a biologically realistic olfactory cortex in analog VLSI

This paper reviews the problem of translating signals into symbols preserving maximally the information contained in the signal time structure. In this context, we motivate the use of nonconvergent dynamics for the signal to symbol translator. We then describe a biologically realistic model of the olfactory system proposed by W. Freeman (1975) that has locally stable dynamics but is globally chaotic. We show how we can discretize Freeman's model using digital signal processing techniques, providing an alternative to the more conventional Runge-Kutta integration. This analysis leads to a direct mixed-signal (analog amplitude/discrete time) implementation of the dynamical building block that simplifies the implementation of the interconnect. We present results of simulations and measurements obtained from a fabricated analog VLSI chip.