An Electrolyte-Gated InGaZnO Phototransistor that Emulates Visual Experience-Dependent Plasticity

Inspired by neurobiological learning rules, bionic devices that simulate the fundamental functions of synapses and neurons provide a highly effective approach to neuromorphic computing. Among various learning rules, the Bienenstock-Cooper-Munro (BCM) learning rule can explain the threshold sliding effect of synaptic weight modification in the visual cortex, which is difficult to explain with the classical Hebb's rule. Existing research mainly focuses on exploiting electrical stimulation to implement the BCM rule, while the optical implementation is still unexplored. In this paper, the light-history-dependent BCM learning rule is implemented with electrolyte-gated InGaZnO (IGZO) transistors. The channel conductance can be modulated through light illumination and electrical stimulation. By utilizing the light-history-dependent property of the IGZO electrolyte-gated transistor and following the triplet-spike-timing-dependent plasticity (STDP) rules, the BCM learning rule is successfully emulated in a single device. Moreover, the light-history-dependent property enables a variety of bionic vision functions including image edge detection and associative memory. This work provides a paradigm for the novel implementation of the BCM rule and paves the way for further development of machine vision systems.