Henry Gustav Molaison (February 26, 1926 – December 2, 2008), known widely as H.M., was an American man who had a bilateral medial temporal lobectomy to surgically resect the anterior two-thirds of his hippocampi, parahippocampal cortices, entorhinal cortices, piriform cortices, and amygdalae in an attempt to cure his epilepsy. Although the surgery was partially successful in controlling his epilepsy, a severe side effect was that he became unable to form new memories.
The surgery took place in 1953 and H.M. was widely studied from late 1957 until his death in 2008. He resided in a care institute in Windsor Locks, Connecticut, where he was the subject of an ongoing investigation. His case played an important role in the development of theories that explain the link between brain function and memory, and in the development of cognitive neuropsychology, a branch of psychology that aims to understand how the structure and function of the brain relate to specific psychological processes.
Molaison’s brain was kept at the University of California, San Diego where it was sliced into histological sections on December 4, 2009. It was later moved to The M.I.N.D. Institute at UC Davis. The brain atlas constructed was made publicly available in 2014.
One morning of 1953, a young man called Henry woke up in a hospital in Hartford, Connecticut. He could not remember why he was there — the memory was hazy. A doctor came in to greet him and congratulate him that the operation was successful and his condition would be most likely cured. Half an hour later, the doctor came back to check, but Henry had no recollection of who he was. Something seemed amiss.
Eighteen years earlier, Henry was walking home from the park. A cyclist hit him and knocked him on the ground. Shortly after the accident, he started experiencing seizures.
The seizures got worse over time and by the time he was 27, he was severely epileptic, sometimes with multiple uncontrollable seizures a day. The condition was debilitating and no treatment was working on him. Dr. William Beecher Scoville, a renowned neurosurgeon, proposed to perform an experimental brain operation on him, offering some hope that epilepsy would go away by removing deep-seated structures in his brain.
In a lobotomy operation gruesome by today’s standard, Dr. Scoville removed significant portions of Henry’s amygdala and hippocampus, the inner part of the temporal lobe while the anesthetized but conscious Henry sat in the operating chair.
After the operation, Henry would entertain himself in the hospital by doing jigsaw puzzles. Except he would do the same one over and over again without realizing he had already done it. His seizures were cured, but his world had been turned upside down. He could no longer form memories that lasted more than 30 seconds.
For the next 50 years, Henry Molaison or H.M. volunteered countless hours to do his tests and became the most studied and famous patient in the history of neuroscience.
Interestingly, his other mental functions such as language and IQ remained intact. He still had memories from his years before the operation. His general knowledge about the world, or semantic knowledge, was functional. But he could not tell what happened at a particular time or place; he had lost his episodic memory.
This indicates that there are different memory systems that support autobiographical memory—a unique event at a specific time and place—and another memory system that supports the “gist” knowledge.
In a surprising experiment, Henry Molaison could remember some celebrities from the post-operative period. It was speculated that the emotional impact these people had on him helped the memory get stuck in his mind.
Dr Brenda Milner, a psychologist from McGill University, performed a famous experiment where HM learned to trace a star reflected in a mirror. It was a groundbreaking result because it showed that his motor memory was intact. It proved that declarative memory, formed in the hippocampus, is separate from motor skills. That’s why when you learn how to ride a bike, you never really forget it, unlike facts.
The damage to Henry’s amygdala did affect other behaviors, and in particular, he seemed to be out of touch with his internal states. He did not seem to experience hunger, fear, or pain.
Despite his severe memory problems, he was not helpless and he remained cheerful. He still worked, albeit in a special center. Yet, there are tragic stories from his life. He couldn’t remember when his father died. From day to day, he couldn’t remember if his parents were alive or not. He wrote notes to remind himself and sometimes, reading them would give him fresh waves of grief. It was like finding out the tragic news over and over again. Kind of like a goldfish swimming around a pool. Since the goldfish has no memory, each trip is a new experience.
His case revolutionized our understanding of memory. We now know that memory is processed by specialized brain areas and compartmentalized in the brain. The ability to form new long-term memories is located in the hippocampus. Another groundbreaking contribution was that there are different kinds of memory residing in different parts of the brain.
Henry Molaison died in 2008 and donated his brain to science. Professor Suzanne Corkin, who studied H.M over the decades, had gathered a team of scientists and MRI specialists to perform an autopsy on H.M.
In December 2009, Jacopo Annese, of The Brain Observatory at the University of California San Diego, and his team dissected H.M.’s brain into 2,401 thin tissue slices that were then preserved cryogenically in serial order. His brain yielded the first open-access, high-resolution, three-dimensional atlas of the human brain.
While the brain was being sliced, the researchers collected digital images of the surface of the block, corresponding to each tissue section. These images were used to construct a three-dimensional microscopic model of the whole brain.
After 5 years of study, they published the results in a Nature Communication paper “Postmortem examination of patient H.M.’s brain based on histological sectioning and digital 3D reconstruction”. They demonstrated that in fact, half of H.M.’s hippocampus had survived the 1953 surgery. This might lead to reinterpretations of H.M.’s neurobehavioral profile and of the existing literature. They also discovered a lesion in the pre-frontal cortex that had not been detected before.
While Henry Molaison would forget every 30 seconds how important he was, the world will undoubtedly remember his contribution to neuroscience a lot longer than he ever could.
Band of Brothers
Four Jewish brothers left home for college, and eventually they became successful doctors, and lawyers and prospered. Some years later, they chatted after having dinner together. They discussed the gifts that they were able to give to their elderly mother, who lived far away in another city.
The first said, “I had a big house built for Mama.”
The second said, “I had a hundred thousand dollar theater built in the house.”
The third said, “I had my Mercedes dealer deliver her a SL 600 with a chauffeur.”
The fourth said, “Listen to this. You know how Mama loved reading the Torah and you know she can’t anymore because she can’t see very well. I met this Rabbi who told me about a parrot that can recite the entire Torah. It took twenty rabbis 12 years to teach him. I had to pledge to contribute $100,000 a year for twenty years to the shul, but it was worth it. Mama just has to name the chapter and verse and the parrot will recite it.”
The other brothers were impressed.
After the holidays Mama sent out her Thank You notes.
Milton – Bubbeleh, the house you built is so huge, I live in only one room, but I have to clean the whole house. Thanks anyway.
Marvin – Mine Shayne Kindeleh. I am too old to travel. I stay home. I have my groceries delivered, so I never use the Mercedes and the driver you hired is a shmendrik. The thought was good. Thanks.
Menachem – Tataleh, you give me an expensive theatre with Dolby sound, it could hold 50 people, but all my friends are dead. I’ve lost my hearing and I’m nearly blind. I’ll never use it. Thank you for the gesture just the same.
Dearest Melvin – You were the only son to have the good sense to give a little thought to your gift. That chicken was delicious.