Spike timing-dependent synaptic plasticity using memristors and nano-crystalline silicon TFT memories

Neural circuits based on ambipolar nano-crystalline silicon TFTs and memristive synapses are investigated via SPICE simulations. The drive transistor for the memristive devices is an ambipolar TFT with memory that could be physically implemented using a metal nanoparticle layer within the gate dielectric. It is shown that using such a device adds spike-timing dependence to changes in the synaptic weight. In experiments with action potential pairs, the synaptic weight modification is similar to biological data. Further, asymmetric temporal integration of the weight change is demonstrated using pre-post-pre and post-pre-post spike triplets. Finally, the dependence of weight changes on frequency is presented. This is followed by a discussion of applications and issues which require further analysis.