By Asmita Anand
Published 4:40 PM EST, Sun May 23, 2021
In recent decades, scientists have made huge progress discovering how our identities, and memories are made and stored. A patient that transformed our understanding of the way memory functions are organised in the human brain, is referred to as ‘the man who couldn’t make memories’; Henry Molaison possessed one of the most famous brains worldwide and bestowed unique insights into the inner-workings of human brains.
Who Was He?
Figure 1: HM in 1953 before his surgery (https://en.wikipedia.org/wiki/Henry_Molaison)
Henry Gustav Molaison, also known in medical literature as patient H.M. to protect his identity, was born on February 26, 1926 in Manchester, Connecticut.
As a child, he had a relatively normal childhood. Although it wasn’t long after a minor head injury and a family history of seizures (although the exact aetiology behind his seizures remains uncertain), that Molaison began suffering from severe epilepsy. At the age of 10, he started having absence seizures and 6 years later he developed generalised tonic-clonic seizures. His seizures greatly impacted his daily life and led him to drop out of high school. Later he was also unable to maintain his job and function independently. Molaison’s case was so severe that it couldn’t be treated pharmacologically with high doses of anticonvulsant medication.
After nearly 10 years he turned to Dr William Scoville, a renowned daredevil neurosurgeon of his time, with hope to lead a normal life once again. At the age of 27, his hippocampus was removed in an experimental procedure in an attempt to alleviate the impact his seizure had on the quality of his life. He underwent a ‘bilateral medial temporal lobectomy’, which surgically removed the medial temporal lobe on both sides of his brain. This included the hippocampal complex, parahippocampal gyrus, the uncus, the anterior temporal cortex, and the amygdala, according to Scoville’s own illustrations of his surgical technique. However in around 1992-199, MRI scans revealed that the surgery was less extensive than he thought, but enough to cause the damage it did. 
Figure 2: Diagram depicting HM’s brain after surgery compared to a normal human brain (https://thepsychologist.bps.org.uk/volume-26/edition-8/looking-back-understanding-amnesia-it-time-forget-hm)
Although Dr Scoville hoped it would cure the epilepsy, he still wasn’t completely sure whether it would be successful or if there might be any long lasting side effects of this procedure. As a result, both of his thoughts were correct. Molaison’s seizures had stopped but unfortunately he was also left with long term memory loss, leaving him constantly living in the present tense. Later Scoville admitted that the operation was a tragic mistake and has spoken strenuously about the dangerous implications of bilateral mesial temporal lobe surgery.
Different types of Amnesia
There are multiple types of amnesia, such as Retrograde, Anterograde, Transient global and Infantile amnesia. Retrograde amnesia is when someone is unable to recall events that occurred before the development of the amnesia and is commonly used in films and media.  Whereas anterograde amnesia refers to a decreased ability to retain new information and is typically caused by brain trauma. 
Molaison developed a peculiar form of amnesia and suffered from both partial retrograde amnesia and anterograde amnesia. The latter meant he lost the ability to form new memories, such as the inability to remember what he had eaten for lunch that day, tests that he just done minutes before and names he had just been introduced to. Scoville wrote: “After operation this young man could no longer recognise the hospital staff nor find his way to the bathroom, and he seemed to recall nothing of the day to day events of his hospital life. There was also a partial retrograde amnesia.”  This meant that while he could recall memories from his childhood, he was unable to remember almost 11 years of events prior to the operation.
However, both his personality, intellectual abilities and perception remained unaffected and his IQ increased from 104 to 117.  Molaison still had the ability to form non-declarative memories, allowing him to still acquire and develop motor skills, which led to Brenda Milner’s discovery of the distinction between procedural and declarative memories. While his mind became like a sieve, through other testing performed by Milner she discovered that he still possessed short term memory. This led to the notion that this too existed in a separate brain structure to the one he lacked.
Short Term and Long Term Memory
Molaison’s misfortune ended up as a milestone in our understanding of the brain as up until it occurred memory wasn’t thought to be localised in one area of the brain. Dr Scoville and Brenda Milner were the first to make observations and report his case in 1957 in the “Loss of recent memory after bilateral hippocampal lesions”. Since he had difficulty remembering doing the tests in the day, Molaison never grew tired of the numerous experiments he partook in.
It is thanks to Molaison, that today we know that intricate functions are directly connected to distinct regions of the brain. The hippocampus, which is embedded deep into the temporal lobe, plays an important role in forming, retaining, and recalling declarative memories and spatial relationships. It’s also where short-term memories are turned into long-term memories.
Five decades later, referred to as Patient H.M., Molaison’s case grew in popularity due to the publication, which has thoroughly been cited numerous times. Researchers arrived at the conclusion that short term memory was not connected in any way to the medial temporal lobe structures. A particular researcher out of the 100 who studied him, Suzanne Corkin, spent the most time with Molaison interviewing him and working with him for 46 years. In her book “Permanent Present Tense: The man with no memory, and what he taught the world”, Dr Corkin covers how Molaison’s mind was used to understand how our minds and memory work. It also covers his early life and key childhood memories from their personal conversations or careful reporting and research. She wrote about how she went from viewing him as a “subject” to seeing him as a human being. Molaison’s life was not easy as he often struggled at times. After a while he came to understand that while others could retrieve and store memories, he could not. Nevertheless, he remained positive, coping well with his difficult situation and he acts as a true inspiration for his extreme resilience. H.M. once poignantly remarked that “every day is alone in itself. Whatever enjoyment I’ve had, and whatever sorrow I’ve had”. 
Figure 3: Photography by Spencer Lowell (https://www.discovermagazine.com/mind/the-art-and-science-of-slicing-up-a-human-brain)
Sadly Henry Molaison passed away at the age of 82 due to respiratory failure. Despite his death in 2008, his brain still continues to excite and offer further investigation into memory as there is still much to uncover. Mr Molaison was much, much more than a research specimen but a person who despite facing grave misfortune, still managed to show ‘the world you could be saddled with a tremendous handicap and still make an enormous contribution to life.’  Columbia pictures and Scott Rudin have even acquired rights to develop a film based on his life.
As Dr Corkin described as “a beautiful finale to his enduring contributions”, his frozen brain was cut into 2,401 slices postmortem, which have been photographed and digitised into a high-resolution, 3D model for further anatomical analysis, in which we can even view individual neurons!
Molaison once commented: “It’s a funny thing – you just live and learn. I’m living and you’re learning.” Henry Molaison leaves behind a legacy (quite literally through the preservation of his brain!) which shall be remembered by us all and stay within our own memories. His forgetfulness has revolutionized our understanding of the brain, which we can still learn so much from till this date.
To end, as Dr Corkin said “Henry’s disability, a tremendous cost to him and his family, became science’s gain”.
Asmita Anand, Youth Medical Journal 2021
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