VLSI Implementation of a Neural Model Using Spikes

The paper presents a VLSI approach to approximate thereal-time dynamics of a neuron model inspired from the classicalmodel of Hodgkin and Huxley, in which analog inputs and outputsare represented by short spikes. Both the transient and the steady-statebehaviours of these circuits depend only on process-independentlocal ratios, thus enabling single or multiple-chip VLSI implementationsof very large analog neural networks in which parallelism, asynchronyand temporal interactions are kept as important neural processingfeatures. Measurements on an integrated CMOS prototype confirmexperimentally the expected electrical and temporal behavioursof the proposed neural circuits and illustrate some outstandingfunctional features of the neural model: spike-mediated modulationof the neural activity, self-regulation of the total activityin neural groups, and emulation of temporal interaction mechanismswith well controlled time constants at different scales.