1. A method of operating a connection configured to communicate an input to an artificial spiking neuron, said method comprising: determining an efficiency associated with operating said connection in accordance with a first plasticity mechanism; and based at least in part on an indication, operating said connection in accordance with a second plasticity mechanism; wherein: said indication is based at least in part on a comparison of said efficiency to a target efficiency; said first plasticity mechanism comprises a common portion and a first adjustable portion; said second plasticity mechanism comprises said common portion and a second adjustable portion; and said second adjustable portion comprises a time-shifted version of said first adjustable portion.