Medicine got its greatest boost in the 1800’s, especially after Louis Pasteur (1822-1895) came up with the theory that diseases were caused by micro-organisms. The new field of bacteriology continued with Pasteur’s friend Joseph Lister (1827-1912), who introduced the novel idea of antiseptic conditions in surgery -- especially washing one’s hands!

Charles Bell (1774-1855) and François Magendie (1783-1855) independently clarified the distinction between sensory and motor nerves. They noted that sensory fibers enter the posterior roots of the spinal cord, and motor fibers leave the anterior roots. Bell is also the first person to describe the facial paralysis we now call Bell's palsy. And Magendie was the first to test the cerebellum's functions.

Franz Joseph Gall (1758-1828) of Vienna and, later, Paris, studied the shapes of skulls and concluded that the various bumps and depressions in each person's head related to certain psychological and personality characteristics. This would become very popular as phrenology, even though serious scientists such as Bell and Flourens thought it absurd. (For a phrenological map of the head, click here. Please don't misunderstand: There is little, if any, truth to this map!)

Marie-Jean-Pierre Flourens (1794-1867) concluded that the cerebrum was in fact responsible for thought and will, and that it operates holistically -- not as Gall would have it! He noted that the other parts -- cerebellum, medulla, etc. -- had different functions, but that each also works holistically within itself. It is also Flourens who introduced ablation -- the removal or destruction of particular parts of an animal's brain -- as a way of studying the connection between the brain and behavior.

However, things just never seem to be simple. Paul Broca (1824-1880), a French surgeon, had a patient that lost the power of speech due to a lesion in what is now called Broca’s Area. Another surgeon, Carl Wernicke, published a book on aphasia in 1874. He, of course, discovered the significance of Wernicke's area by doing an autopsy of a patient who had lost the ability to comprehend speech.

In 1870, two researchers, Gustav Fritsch and Eduard Hitzig, used direct electrical stimulation of the brain in a dog to discover, among other things, the motor and sensory cortices. Four years later, Robert Bartholow did the same with a human brain. Their work established that there is indeed some localization of function -- it just doesn’t have anything to do with bumps on the head.

Johannes Müller (1801-1858), working in Berlin, developed the doctrine of specific energy of nerves. Each nerve, when stimulated, leads to only one sensory experience, even if it is stimulated in another manner than usual. A simple example is the light flashes you see when you press against your eyeballs! This (I think unfortunately) led to increased belief in indirect realism -- i.e. that we don’t actually experience the world directly, much less accurately.