Scientists have known since the 18th century that living beings can generate electricity. By the 19th century, doctors were putting that knowledge to use in medicine.
In 1838, Irish physician Robert Bentley Todd observed an experiment by British scientist Michael Faraday that measured the jolt of an electric eel. Todd went on to apply Faraday’s concept of the “electrical force” to his study of the human nervous system.
Todd refuted theories that epilepsy was caused by vascular issues or inflammation. Instead, he posited that it was caused by rapid electrical discharges “exciting the other parts of the brain and spinal cord with all the violence of the discharge from a highly charged Leyden jar,” an early type of capacitor.