1. A method for reinforcement learning, the method comprising: receiving at least one reinforcement signal from at least one spiking neuron of a neural network comprising multiple neurons interconnected by multiple synapse devices, wherein each reinforcement signal corresponds to a past event involving an action, and the reinforcement signal represents a reward indicating success of the action; and balancing spiking in the neural network based on the at least one reinforcement signal, wherein the balancing comprises adjusting interconnectivity between the multiple neurons by modulating one or more axonal target addresses that one or more neurons of the neural network are programmed to route spike signals to or receive spike signals from, each axonal target address comprising an address of an axon interconnected to a neuron of the neural network, and each axon, in response to receiving a spike signal routed to an axonal target address of the axon, delivering the spike signal to an interconnected neuron.