H.M. (patient)

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Revision as of 17:30, 17 April 2008

H. M. is the single most famous case study in the history of neuropsychology. H. M. is an anonymous memory-impaired man, who is only referred to by his initials of H.M. (his real name was Henry). H. M. has one of the most severe cases of amnesia ever recorded, and has been observed by over 100 researchers for over 40 years.

History

H.M was born in Hartford, Connecticut in 1926. He suffered from severe epilepsy, that has often been atributed to a bicycle accident at the age of 9, where he lost consciousness for 5 minutes. He began experiencing mild seizures, and had his first major seizure on his 16th birthday. He also had a family history of epilepsy stemming from his father's side. Into his late 20's, H.M. was experiencing up to 10 seizures and blackouts a week. His seizures were becoming incapacitating and he seemed to be unresponsive to anti-epileptic medications, even at maximum dosages.

Surgery

In 1953, at the age of 27, H.M. was referred to William Beecher Scoville, founder and director of the Department of Neurosurgery at Hartford Hospital. Dr. Scoville localized H.M.'s seizures to the temporal lobe, and on September 1st of that same year, he performed an experimental surgery on H.M. called a bilateral medial temporal lobe resection, removing parts of the temporal lobe from both hemispheres. The resection ultimately removed H.M.'s amygdala, entorhinal and perirhinal cortices, and two-thirds of his hippocampus (see below).

Amnesia

H.M.'s surgery was successful in alleviating his symptoms, and he only had about 2 seizures per year after his surgery. H. M. was, however, left with profound memory difficulties. He has severe anterograde amnesia, and partial retrograde amnesia. He cannot form new long-term memories since his surgery, and cannot acquire new knowledge about anything going on around him or in the world. He does, however, know that he has some kind of illness, and that he is contributing something by allowing researchers to study him. Despite H.M.'s amnesia, he remembers most all of his childhood memories, and can even correctly draw a foorplan of the house he grew up in. He also has an above average IQ of 118, and his capacity for language seems to be perfectly intact. H.M. has also proven to be able to learn simple sensorimotor skills: his performance improves with practice on a task involving him to trace a simple diagram by looking at its reflection in a mirror. H.M., of course, never remembers seeing or completing this task, though his performance is improving. H.M. was even able to hold a simple job at the residential home where he lived, though he couldn't describe his job after working there for 6 months.

Contributions

H.M. Today