Brain Waves and Brain Stimulation

Although spontaneous and evoked electrical activity was identified in the brains of animals and human subjects in the late nineteenth century, it was not until the electronic advances of the early twentieth century that the clinical application of electroencephalography (EEG) was appreciated. Hans Berger first identified rhythmic alpha activity in human subjects and Adrian later concluded it was a default rhythm that occurred when subjects were inattentive. EEG proved most useful for diagnosing seizure disorders and neurosurgeons soon began using it to localize the seizure discharge prior to surgical resection. William Penfield revolutionized the surgical treatment of epilepsy at the Montreal Neurological Institute using electrical stimulation of the cortex in awake patients to decide which areas were safe to resect. Although initially used to treat schizophrenia, electroconvulsive therapy proved most effective for treating severe depression. Major concerns about safety remain despite continued use. Because of its rapid action compared to antidepressant medications, it is most used for treating patients at high risk for suicide. Deep brain electrical stimulation has a checkered past regarding both science and ethics, but it has established benefit for treating movement disorders such as dystonia and Parkinson disease. The benefits for treating psychiatric disorders are promising but to be established.