Demonstration of Pavlov associative memory by implementation of rate coding using magnetic tunnel junction neurons

Abstract

In this article, a fully functioning Pavlov associative memory system, one of the most famous examples of biological brain function, is implemented by a basis of rate coding. In order to create a neural signal that is capable of emulating the synaptic weight based on rate coding, a neural signal is constructed by utilizing telegraphic switching of the magnetic tunnel junction (MTJ), a random magnetization reversal phenomenon. The spike rate of the MTJ neuron is controllable by adjusting the spin-torque-transfer (STT) current bias, creating signals with rate information that is capable of implementing rate coding scheme as a weight update method for the TiO2 memristor synapse. The proposed neuron creates random spike signals containing rate information, which participates in emulating Pavlov associative memory characteristics such as learning and forgetting, as well as rate controlling characteristics. The suggested structure shows a coding scheme that both input and output neurons participate, which can be expanded to larger neuromorphic neural network applications.