A Mixed-Signal Structured AdEx Neuron for Accelerated Neuromorphic Cores

Abstract

Here, we describe a multicompartment neuron circuit based on the adaptive-exponential I&F (AdEx) model, developed for the second-generation BrainScaleS hardware. Based on an existing modular leaky integrate-and-fire (LIF) architecture designed in 65-nm CMOS, the circuit features exponential spike generation, neuronal adaptation, intercompartmental connections as well as a conductance-based reset. The design reproduces a diverse set of firing patterns observed in cortical pyramidal neurons. Further, it enables the emulation of sodium and calcium spikes, as well as N-methyl-D-aspartate plateau potentials known from apical and thin dendrites. We characterize the AdEx circuit extensions and exemplify how the interplay between passive and nonlinear active signal processing enhances the computational capabilities of single (but structured) on-chip neurons.