An aVLSI programmable axonal delay circuit with spike timing dependent delay adaptation

We present measurements from an aVLSI programmable axonal propagation delay circuit. It is intended to be used in the implementation of polychronous spiking neural networks. The delay can be programmed by presenting an input spike followed by a training spike at the desired delay. To fine tune and maintain the delay using an analogue memory, we use continuous spike timing dependent delay adaptation. Measurements presented here show that the axon circuit is capable of learning and retaining delays in the 2.5-20 ms range, as long as the neuron is stimulated at least once every few seconds.