1. In a simulated nervous system network having a first pre-neuron and a second post-neuron, and a synaptic pathway between the first pre-neuron and the second post-neuron having synaptic strength (s) and an eligibility trace (c), a method for determining a firing pattern of the first pre-neuron and the second post-neuron, comprising: (a) firing the first pre-neuron and the second post-neuron to induce changes to the synaptic strength (s) according to a spike-timing-dependent plasticity (STDP) rule; and (b) providing extracellular dopamine to the synaptic pathway during a window of time after the firing and the eligibility trace (c) decays to zero.