One aspect of the invention relates to a multi-terminal memtransistor. The memtransistor includes a substrate having a first surface and an opposite, second surface, a polycrystalline monolayer film formed of an atomically thin material on the first surface of the substrate, an electrode array having a plurality of electrodes spatial-apart formed on the polycrystalline monolayer film such that each pair of electrodes defines a channel in the polycrystalline monolayer film therebetween, and a gate electrode formed on the second surface of the substrate and capacitively coupled with the channel. The polycrystalline monolayer film contains grains defining a plurality of grain boundaries thereof. The multi-terminal memtransistor operates much like a neuron by performing both memory and information processing, and can be a foundational circuit element for new forms of neuromorphic computing.