Henry Molaison, often referred to as H.M., was a man who became famous in the field of neuroscience after undergoing brain surgery in 1953 to treat his severe epilepsy. The surgery involved the removal of parts of his hippocampus, which resulted in profound memory loss. While he could recall memories from before the surgery, he was unable to form new long-term memories, a condition known as anterograde amnesia. H.M.'s case provided valuable insights into the workings of memory and the brain. Researchers studied him for decades, leading to significant advancements in understanding how different types of memory are processed. His unique condition has made him a key figure in the study of neuroscience and memory disorders.