The human body is a complex organization that, to function, requires continuous transfer of information between its parts. Many of the biomedical signals of interest to us are, in some form, a measurement of this process. The transfer of information through nerves and in the brain is an electrochemical process, whose basic component is neuronal transmission. Unlike the almost instantaneous transmission of an electrical signal through a wire, the transmission of a signal through a neuron is both complex and relatively slow. The transmission of a signal is initiated by a change of electrical polarization across the neuronal membrane, called the action potential, which then triggers a sequence of action potentials in a domino-like fashion along the axon. This sequence of action potentials is the neuronal transmission of information. In this chapter, we briefly examine the somewhat convoluted history of the discovery of neuronal transmission mechanisms and, again briefly, describe the process of neuronal transmission.