HM (patient)

HM (or Henry Mr.) is the Pseudonyme of a patient (born in 1926) become Amnésique following an surgical operation carried out by William Scoville in 1953. Since 1957, he was largely studied by the Neuropsychologue S, in particular Brenda Milner and Suzanne Corkin during second half of the 20th century and so largely contributed to our comprehension of the mechanisms of the memory.

History

Suffering from epilepsy resistant to the drugs, HM underwent an experimental surgical operation consisting in bilaterally withdrawing to him a broad portion of both hippocampi and surrounding fabrics of the temporal lobes, where Scoville thought that the hearths epileptogenes were localized. Since its alarm clock HM suffers from a quasi total anterograde amnesia while at the same time its short-term memory, known as short-term Mémoire is intact: it is unable to retain information beyond a few seconds unless making a constant effort of repetition. HM is thus unable to memorize new information in manner clarifies even if later experiments showed that it preserved part of its implicit Mémoire in particular driving. New studies also show that he remembers sometimes some certain very specific information like the fact that he has " problems of mémoire" or that " a famous person called Kennedy was assassinée" (Corkin, 1984). Even if these memories are extremely rare, they indicate that the anterograde amnesia is not a phenomenon repeating spring. One allots his capacity to retain certain information like the plan of his new house, his face in the ice or the fact that his/her parents died, by their very repetitive character or with strong emotional load. The emotion and the repetition would indeed make it possible to use other structures of the cortex for their memorizing. (Eichenbaum 2000).

Causes

The anterograde amnesia from which HM suffers accompanies by a lighter retrograde amnesia of approximately 11 years (Corkin, 1984). In a more precise way, it is often accepted that the bilateral résection of the hippocampi was the cause of these mnemic disorders. However recent research (Corkin, 2002) tends to show that this amnesia is also related to the fact that zones extrahippocampales, were injured at the time of the operation. Eichenbaum (2001) watch indeed that the Cortex périrhinal would significantly be implied of the process of |memorizing clarifies, whereas the |hippocampus would have a role more restricted of comparison of the perceived elements. In a general way, the various assumptions of the causes of the amnesia of HM are difficult to test because the zones of the brain damaged are relatively vast. Of another case (RB, GD, LM, WH) were however correlated by Duyckaerts et al. in 1985.

Today

In 2006, HM is always alive and takes part still punctually in experiments of psychology. More than fifty years after the operation, its mnemic disorders evolved/moved very little. In spite of its disorders of memory, HM is a very courteous person, and does not suffer from problem of identity. However, it is very difficult for him to know if it is hungry, sleep or badly at a precise place. It resides in an institution of care at Hartford, in the Connecticut.

Bonds

Neuropsychology
memory
episodical hippocampus
Memory
declaratory Memory
Amnesia

External bonds

Reference general:

Brown MW and Aggleton JP (2001) Recognition memory: what are the roles off the perirhinal cortex and hippocampus? , Natural Reviews Neuroscience, 2:51 - 61
Croisile, B (2006) H.M., or 50 years of amnesia! , Neuropsychology, 379
Murray EA and Richmond BJ (2001) Role off perirhinal cortex in object perception, memory, and associations, Current Opinion in Neurobiology, 11:188 - 193
Murray EA and Bussey TJ (1999) Perceptual-mnemonic functions off the perirhinal cortex, Trends in Cognitive Science 3:142 - 151
Eichenbaum (2001), The hippocampus and declaratory memory: cognitive mechanisms and neural codes, Behavioral Brain Research 127:199 - 207.
Eichenbaum H (2000), Natural Reviews Neuroscience 1:41 - 50
Corkin S (2002) What' S new with the amnesic patient H.M.? Nature Reviews Neuroscience, 3:153 - does 160
Murray EA (1996) What cut ablation studies told custom butt the neural substrates off memory? Seminars in the Neurosciences, 8:13 - 22

Reference specific:

Murray EA and Mishkin M (1998) Object recognition and localization off memory in monkeys with excitotoxic lesions off the amygdala and hippocampus, Newspaper off Neuroscience. 18:6568 - 6582
Wan H, Aggleton JP, Brown MW (1999) Different contributions off the hippocampus and perirhinal cortex to recognition memory, Newspaper off Neuroscience 19:1142 - 1148
Buckley M and Gaffan D (1998) Perirhinal odd cortices ablation visual object identification, Newspaper off Neuroscience 18:2268 - 2275
Gaffan D (1992) Naturalistic scenes and fornix transection, European Newspaper off Neuroscience, 4:381 - 388
Bunsey M and Eichenbaum H (1996) Conservation off hippocampal memory formation in rats and humans, Natural 18:255 - 257

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