Ever since the physician Scribonius Largus slapped an electric torpedo fish on the forehead of a headache sufferer in the early days of the Roman empire, electricity has been pursued as a cure for a seemingly endless variety of ailments–by serious scientists and profiteering quacks alike. The latest chapter in this long and colorful history (see sidebar below) involves something called transcranial direct current stimulation, in which a small electric current is delivered to the brain through electrodes...
