This post by Neurophilosophy called Remembering Henry M is fascinating (and is a must-read, too):
The single most famous case study in the history of neuropsychology is that of an anonymous memory-impaired man usually referred to only by the initials H. M. This patient has one of the most severe cases of amnesia ever observed; he has been followed for over 40 years by more than 100 researchers, and is the subject of dozens of research papers and book chapters. The early studies of H. M. provide a basis for modern neuropsychology, and the findings of those who have studied him are today a cornerstone in memory research.
It goes on to recount his medical history, and its implications to neuro-research. Here is the concluding paragraph of the post:
H. M. appears to be missing those parts of the brain that are crucial for the formation of both declarative and episodic memories, but at least some components of the neural circuitry encoding spatial memories are still present. H. M. is an invaluable source of information for memory researchers. He is now 80 years old, and suffers from osteoporosis, a side effect of phenytoin, the anti-convulsive drug he has been taking. Otherwise, he is in good health. But death is, of course, inevitable, and arrangements have already been made for post-mortem examination of his brain. Undoubtedly, an examination of H. M.’s brain will reveal a great deal more about the anatomy of memory.
While you are at Neurophilosophy, you might also want to take a look at this post, where MC links to a neurophilosophy book (called Subjective Brain) draft that is available online. Have fun!