Large Developing Receptive Fields Using a Distributed and Locally Reprogrammable Address–Event Receiver

A distributed and locally reprogrammable address–event receiver has been designed, in which incoming address–events are monitored simultaneously by all synapses, allowing for arbitrarily large axonal fan-out without reducing channel capacity. Synapses can change the address of their presynaptic neuron, allowing the distributed implementation of a biologically realistic learning rule, with both synapse formation and elimination (synaptic rewiring). Probabilistic synapse formation leads to topographic map development, made possible by a cross-chip current-mode calculation of Euclidean distance. As well as synaptic plasticity in rewiring, synapses change weights using a competitive Hebbian learning rule (spike-timing-dependent plasticity). The weight plasticity allows receptive fields to be modified based on spatio–temporal correlations in the inputs, and the rewiring plasticity allows these modifications to become embedded in the network topology.