Henry Molaison, known to the scientific community as "Patient H.M.," was a 27 year old man who suffered from recurring epileptic seizures after a childhood bicycle accident. In an experimental attempt to cure his epilepsy, a neurosurgeon named William Beecher Scoville performed a lobotomy on Molaison which resulted in a complete loss of his ability to form long-term memories.
In the years after his procedure, Molaison became a major research focus for neuroscientists. Dr. Brenda Milner, a neuropsychologist from the Montreal Neurological Institute, evaluated Molaison and found that though his epilepsy was under control, he could not recall events that had occurred only five minutes prior. Molaison himself reported that his life felt "like waking from a dream...every day is alone in itself."
Anatomy of the brain; the hippocampus is located in the temporal lobes
Image Credit: THEPALMER
Molaison served as a research subject for 55 years and much of what the scientific community understands about memory stems from research involving him. While he was unable to form new explicit memories (easy to recall long-term memory), he was capable of improving motor skills. This indicated that his implicit memory was still intact. The effects of the lobotomy on Molaison's memory connected brain function to structure and the hippocampus became known as a key site for memory storage in the brain.
Henry Molaison's identity was only revealed after his death in 2008. The vulnerability associated with his amnesia prevented scientists from identifying him sooner and patient confidentiality prevailed. To this day, he is still considered to be the most famous patient in the field of neuroscience.