MOSFET implementation of class I* neurons coupled by gap junctions

Abstract

We propose a two-dimensional class I* neuron circuit coupled by gap junctions (GJs) consisting of enhancement-type metal-oxide-semiconductor field-effect-trangistors (MOSFETs). It is shown that some neurons that belong to a subclass of class I, when coupled by GJs, exhibit extensive spatiotemporal chaos in some parameter regions. This subclass is called class I* and is characterized by a phase plane structure with a narrow channel. We can tune our circuit to be class I, I*, or II by changing the resistance values. We show PSpice simulation results for a circuit implemented with discrete elements. A GJ-coupled network consisting of 20 such neurons is shown to generate itinerant dynamics with spatiotemporal chaos similar to class I* GJ-couple systems. The circuitry is compatible with standard complementary metal-oxide semiconductor (CMOS) processes. Hence, it can be implemented in an analog very-large-scale integrated circuit (VLSI) and the construction of a relatively large network is possible.