The firing rate is identified both as a normalized probability for neural spike firing, and as a quantity proportional to the current of neurotransmitters released by the cell. The expression for the firing rate takes the following form:  formula_47  where,   formula_48  P0 could be generally calculated recursively using Euler method, but in the case of a pulse of stimulus it yields a simple closed form expression.  formula_49 , with formula_50 being short temporal average of stimulus power (given in Watt or other energy per time unit). Other predictions by this model include:  1) The averaged Evoked Response Potential (ERP) due to population of many neurons in unfiltered measurements resembles the firing rate. 2) The voltage variance of activity due to multiple neuron activity resembles the firing rate (also known as Multi-Unit-Activity power or MUA). 3) The inter-spike-interval probability distribution takes the form a gamma-distribution like function. The following is a list of published non-Markovian neuron models:   The theta model, or Ermentrout–Kopell canonical model, is a model originally developed to model neurons in the animal Aplysia, and is particularly well suited to describe neuron parabolic bursting. The models in this category produce predictions for experiments involving pharmacological stimulation. According to the model by Koch and Segev, the response of a neuron to individual neurotransmitters can be modeled as an extension of the classical Hodgkin–Huxley model with both standard and nonstandard kinetic currents. Four neurotransmitters primarily have influence in the CNS. AMPA/kainate receptors are fast excitatory mediators while NMDA receptors mediate considerably slower currents. Fast inhibitory currents go through GABAA receptors, while GABAB receptors mediate by secondary "G"-protein-activated potassium channels. This range of mediation produces the following current dynamics:   where is the maximal conductance (around 1S) and is the equilibrium potential of the given ion or transmitter (AMDA, NMDA, Cl, or K), while describes the fraction of receptors that are open. For NMDA, there is a significant effect of "magnesium block" that depends sigmoidally on the concentration of intracellular magnesium by . For GABAB, is the concentration of the "G"-protein, and describes the dissociation of "G" in binding to the potassium gates. The dynamics of this more complicated model have been well-studied experimentally and produce important results in terms of very quick synaptic potentiation and depression, that is, fast, short-term learning.