The neuroscience of Helmholtz and the theories of Johannes Muller Part 1: Nerve cell structure, vitalism and the nerve impulse

Hermann Helmholtz made monumental contributions to the neural sciences in the second half of the nineteenth century. Among his earliest achievements were experiments that challenged vitalism, microscopic studies on the structure of the nerve cell and its processes, and the first reasonable estimates of the speed of nerve transmission based on physiological experiments. In this, the first of a two-part article, we review Helmholtz's early contributions in biographical context and with reference to Johannes Mller's own thoughts.We reveal how Johannes Mller, considered by many to be the greatest physiologist of the first half of the nineteenth century, helped to launch and shape Helmholtz's career. We also show that Helmholtz was only willing to accept some of his mentor's theories, even though he had great admiration for Mller. The point will be made that Helmholtz owed a great debt to Mller, but even from his student days in Berlin he was an independent thinker with his own agenda, and never his strict disciple.