Back in 1948, Shannon introduced Information Theory with his landmark paper “A mathematical theory of communication”. Since then, Neuroscience has been treated by researchers as a major field of application of this new theory, beyond its original scope. A recent special issue of the Journal of Computational Neuroscience on Methods of Information Theory in Neuroscience Research focuses on current methods and applications of Information Theory to neural systems.
You may access this Special issue here: http://www.springerlink.com/content/0929-5313/30/1/
 Shannon CE . A mathematical theory of communication. Bell System Technical Journal 1948;27:623–56.