Introduction to neuromorphic functions of memristors: The inductive nature of synapse potentiation

Memristors are key elements for building synapses and neurons in advanced neuromorphic computation. Memristors are made with a wide range of material technologies, but they share some basic functionalities to reproduce biological functions such as synapse plasticity for dynamic information processing. Here, we explain the basic neuromorphic functions of memristors, and we show that the main memristor functionalities can be obtained with a combination of ordinary two-contact circuit elements: inductors, capacitors, resistors, and rectifiers. The measured IV characteristics of the circuit yield clockwise and counterclockwise loops, which are like those obtained from memristors. The inductor is responsible for the set of resistive switching, while the capacitor produces a reset cycle. By combining inductive and capacitive properties with gating variables represented by diodes, we can construct the full potentiation and depression responses of a synapse against applied trains of voltage pulses of different polarities. These results facilitate identifying the central dynamical characteristic required in the investigation of synaptic memristors.