Analog VLSI neuromorphic network with programmable membrane channel kinetics

We demonstrate neuron spiking dynamics in a small network of analog silicon neurons with dynamical conductance-based synapses. The analog VLSI chip (NeuroDyn) emulates analog continuous-time dynamics in a fully digitally programmable network of 4 biophysical neurons. Each neuron in NeuroDyn implements Hodgkin-Huxley dynamics in 4 variables, with 28 parameters defining the conductances, reversal potentials, and voltage-dependence of the channel kinetics. All 12 chemical synapses interconnecting the neurons also have individually programmable parameters defining conductance, reversal potential, and pre/post-synaptic voltage dependence of the channel kinetics. All configurable parameters in the implemented model have a biophysical origin, thus supporting direct interpretation of the results of adapting/tuning the parameters in terms of neurobiology. Uniform temporal scaling of the dynamics of membrane and gating variables is demonstrated by tuning a single current parameter, yielding variable speed output exceeding real time. The 0.5 mum CMOS chip measures 3 mm times 3 mm, and consumes 1.29 mW.