It is not certain as to which is really the actual physiological phenomenon in each case. However, both cases can be modeled computationally and the parameters varied to match the experimental result. The pulse mode is more complex to model and numerous detailed neuron models and population models are described by Gerstner and Kistler in Parts I and II of Gerstner, W., & Kistler, W. (2002)[1] and Chapter 8 of Sterratt, D., Graham, B., Gillies, A., & Willshaw, D. (2011).[2] Another important characteristic associated with SR model is the spike-time-dependent-plasticity.