Pulse frequency modulation in neural systems. A random model

A model is proposed of the pulse frequency modulation process in those neural systems where the neuron discharge is random. The model is characterized by one property, namely input-invariance of the output random process after a time transformation, which, on the one hand, greatly simplifies its analytical treatment, and on the other hand, gives a tool to determine experimentally whether the model describes the external behavior of a given neural system. The main dynamical properties of the model are studied, and the relevance of the results to information transmission by neural systems is discussed.