Henry Gustav Molaison, or HGM, is one of the most well-known names in the history of neuroscience.
Bicycle accident at age 7 resulted in minor seizures at age 10, more severe seizures at age 16. Although he kept up with his working life for a while, he had difficulty in controlling his seizures despite high doses of drugs. At the age of 27, he decided to try an operation that had previously been performed on patients in the field of psychology. It would be a first in this field and the results of the surgery were not fully known. And on August 25, 1953, he underwent brain surgery complaining of persistent epileptic seizures.
Postoperative epilepsy was largely cured. But removing a large amount of brain tissue, particularly the hippocampus portion, posed an entirely new problem. From then on new events, names, places; In short, he could not create any new memories. Perhaps in the simplest terms, he was just living in the moment. Each day was separate and alone for him, as if waking from a new dream.
“Everything is clear now, but what just happened?” he asked one day. Although he saw the same doctors and nurses every day, he seemed to have just met them all. He was a very intelligent person, but he was not in a position to work or live alone. Without the part about long-term memory, his life was made up of independent moments.
This tragic misfortune had only one benefit, but it was just as great. Neuroscientists have worked with HGM for years to find groundbreaking information about memory formation. Explicit memory—the memory that allows us to consciously recall new memories—could not store new information, but short-term memory, which allows us to recall information up to about 20 seconds, was intact. He could also learn new skills, although he couldn’t remember how he learned it. These findings allowed us to distinguish between procedural memory—nonconscious memory that allows us to perform motor activities such as driving—and explicit memory. The fact that HGM could not form new memories even though childhood memories were intact showed the difference in memory encoding and recall processes. Perhaps most importantly, it turned out that in the absence of the hippocampus, this part of the brain is the part of the brain that encodes long-term expressive memory, but is not required for short-term or procedural memory.
The fact that even when he died in 2008 at the age of 82, the fact that his brain was stored and frozen in very thin pieces to be used for further research is undoubtedly one of the greatest legacies he contributed to science. Although HGM is not currently alive, it continues to lead research and will help us find the unknown for a long time to come. Thank you HGM for this invaluable legacy!
