The functioning of human brain is one of the greatest enigmas of science at present: formed by a net of approximately 10^10 neurons interconnected by 10^15 connections in a volume of just 1500 cm^3, it consists in one of the most complex systems known in the Universe by Mankind. To attack this problem of such complexity, this book attempt to congregate efforts from different areas of knowledge for the development of research ranging from theoretical models in neurobiophysics to scientific instrumentation used in our experimental procedures, working in the frontiers of Physics, Biology, Computer Sciences, Electronics and Mathematics. We have chosen the fly because it has a much simpler nervous system than the human brain, but even so, tremendously complicated. Besides, we can carry out experiments in a living fly through many days without problems, studying particular areas in its brain. Pulses generated by the H1 neuron are electronically registered in synchrony with a moving image seen by the fly in a monitor. We study this signal "converter" from analogical (the velocity of the stimulus) to digital (the neuron pulses) to find out what is the neural code used by the fly.