Models of neural systems should be biologically plausible and statistically efficient. This presentation at the "Summer School on 'Physics and Neuroscience'", at Natal, Brazil, August 2014, rests upon: Galves, A., & Löcherbach, E. (2013). Infinite Systems of Interacting Chains with Memory of Variable Length—A Stochastic Model for Biological Neural Nets. Journal of Statistical Physics, 151(5), 896-921. Lecturer: Prof. Antonio Galves, NeuroMat.