H.M. (Henry Molaison)

H.M., or Henry Molaison, was an American man who became a significant case study in neuroscience after undergoing brain surgery in 1953 to treat epilepsy. The surgery involved removing parts of his hippocampus, which led to profound memory loss. H.M. could no longer form new long-term memories, although his short-term memory and past memories remained largely intact. His case helped researchers understand the role of the hippocampus in memory formation and led to important insights about different types of memory, profoundly influencing the fields of psychology and neuroscience. H.M. lived until 2008, contributing to our understanding of memory and the brain.