Back in 1874 a rather disturbing thing happened that had profound implications for our understanding of the human brain.

It was in Cincinnati that a physician named Robert Bartholow was about to go down in medical history as both a pioneer in the field of neurology and a striking example of how researchers should never behave.

The unhappy subject of Bartholow's experiment was his housemaid, a woman named Mary Rafferty. Miss Rafferty suffered from a cancer that had not only left her without skin over a section of her head but had eaten away the skull as well, leaving part of her brain exposed. Dr. Bartholow used this grim opportunity to insert electrodes directly into her brain and apply a mild electrical current.

This experiment was certainly an unethical one, and Dr. Bartholow was to spend the rest of his life cast out from medical society for putting scientific curiosity ahead of his subject's well-being. However, the results of his unusual experiment were important. Bartholow found that he could cause Mary Rafferty's right arm and leg to contract by stimulating the left side of her brain, and vice versa. Miss Rafferty did not experience any pain in her head, but described a strong and unpleasant sensation in her limbs during the stimulation.

Dr. Bartholow and Mary Rafferty thus became the first people to directly demonstrate what 19th century scientists had already surmised by other means: that electricity is the means by which the brain controls the body. Modern studies with direct brain stimulation are less horrific and more scientific. To hear about what we've learned from them, tune in next time.