Farnood Merrikh-Bayat and Saeed Bagheri at the University of Tehran have connected memristors (memory resistors) together in a way that mimics the wiring of human brains, reproducing Hebbian-type synapse strengthening.

Two simulated neurons connected through a synapse, represented by a memristor (Farnood Merrikh-Bayat and Saeed Bagheri)

Ref: arxiv.org/abs/1008.3450: Bottleneck Of Using Single Memristor As A Synapse And Its Solution

[ the physics ArXiv blog ]