Henry Molaison: How Patient HM Changed What We Know About Memory
Summary
TLDRHenry Molaison, known as Patient HM, underwent a brain procedure in 1953 to cure his severe seizures, which inadvertently left him with anterograde amnesia. The surgery, performed by William Scoville, removed parts of his medial temporal lobe, including the hippocampus, revealing the brain's memory centers. Despite his inability to form new memories, Henry retained his intellect and motor skills. His case became pivotal in understanding the distinction between declarative and non-declarative memory systems, with researchers like Brenda Milner and Suzanne Corkin studying his unique condition. The narrative also touches on the ethical considerations of treating human subjects in scientific research.
Takeaways
- 🧠 Henry Molaison underwent a brain surgery in 1953 to cure severe seizures, which resulted in the removal of parts of his medial temporal lobe, including the hippocampus.
- 🔍 The surgery was performed by William Scoville, a lobotomist who noted that lobotomy could relieve seizures in some patients.
- 💡 The procedure successfully reduced Henry's seizures but left him with anterograde amnesia, unable to form new memories while preserving his intellect and other cognitive functions.
- 🧐 Memory researcher Brenda Milner studied Henry extensively, revealing that memory is localized to specific brain structures rather than distributed throughout the brain.
- 📚 Henry's case helped to establish the concept of the medial temporal lobe memory system, which includes the hippocampus and surrounding cortices.
- 🕵️♂️ Henry's memory loss was selective; he could recall long-term memories from before his surgery but could not form new ones.
- 🤹♂️ Despite his memory issues, Henry was able to learn and retain new motor skills, demonstrating the existence of multiple memory systems in the brain.
- 🔑 The distinction between declarative memory (factual information) and non-declarative memory (skills, habits, emotional memory) was clarified through Henry's case.
- 🧬 Non-declarative memory relies on brain structures like the basal ganglia, amygdala, cerebellum, and neocortex, which were unaffected by Henry's surgery.
- 🏛️ The academic community's relationship with Henry was complex, with some researchers treating him more as a subject than a person, impacting his personal life and legacy.
- 📖 The story of Henry Molaison, known as Patient HM, has been a significant contribution to our understanding of the human brain and memory.
Q & A
What was the reason Henry Molaison underwent a brain surgery in 1953?
-Henry Molaison underwent brain surgery in 1953 to cure his severe and uncontrollable seizures, which had begun after a childhood bicycle accident.
Who was the surgeon that performed the experimental procedure on Henry Molaison?
-The surgeon who performed the procedure on Henry Molaison was William Scoville, a well-known lobotomist at the time.
What part of Henry's brain was removed during the surgery?
-During the surgery, a thumb-sized section of the medial temporal lobe, including the hippocampus, amygdala, and entorrhinal cortex, was removed from both sides of Henry's brain.
What was the immediate effect of the surgery on Henry's seizures?
-The surgery alleviated some of Henry's seizures but left him unable to form any new memories.
How did the surgery affect Henry's intellectual abilities?
-The surgery did not affect Henry's perception or intellect; in fact, he scored higher on IQ tests following the surgery.
Who was the memory researcher from McGill University that studied Henry Molaison?
-Brenda Milner was the memory researcher from McGill University who studied Henry Molaison.
What did Brenda Milner's observations on Henry contribute to our understanding of memory?
-Brenda Milner's observations helped to conclude that memory is not distributed throughout the entire brain but is limited to specific structures, now known as the medial temporal lobe memory system.
What type of memory loss did Henry Molaison experience?
-Henry Molaison experienced anterograde amnesia, meaning he was unable to create new memories while still being able to recall long-term memories from before the surgery.
How did Henry's ability to acquire new motor skills demonstrate the existence of multiple memory systems?
-Henry's ability to learn and retain new complex motor skills, such as mirror drawing, showed that there are multiple memory systems housed in different parts of the brain.
What are the two main types of memory as understood from Henry's case?
-The two main types of memory are declarative memory, which is the ability to recall factual information, and non-declarative memory, which includes skill learning, habit learning, and emotional memory.
Why is Henry Molaison referred to as 'Patient HM' in academic literature?
-Henry Molaison is referred to as 'Patient HM' in academic literature to maintain his anonymity and protect his identity, despite his significant contributions to the study of memory.
What ethical concerns arose from the treatment and posthumous handling of Henry Molaison?
-Ethical concerns include the control over access to Henry by Susanne Corkins, the arrangement of his brain donation, and the perceived lack of empathy shown towards Henry as a person, treating him more as a scientific subject than a human being.
Outlines
🧠 The Story of Patient HM and His Groundbreaking Surgery
In 1953, Henry Molaison, suffering from severe seizures since a childhood bicycle accident, underwent a radical brain surgery performed by Dr. William Scoville. Scoville removed significant portions of Henry's medial temporal lobes, including the hippocampus, amygdala, and entorhinal cortex, in an attempt to control his seizures. While the procedure partially succeeded in reducing the seizures, it also left Henry with profound anterograde amnesia, unable to form new memories but retaining his intellectual abilities and long-term memories from before the surgery. This case would later revolutionize our understanding of memory, highlighting the critical role of the medial temporal lobe.
🔬 The Research Legacy of Henry Molaison
Two years post-surgery, Henry Molaison became a pivotal figure in memory research, extensively studied by Brenda Milner and later by her student, Suzanne Corkin. Milner's early work with Henry revealed that memory is not uniformly distributed across the brain but localized to specific structures in the medial temporal lobe. Henry’s unique condition allowed researchers to discover the distinct nature of declarative and non-declarative memory systems. Despite his inability to form new declarative memories, Henry could still learn and retain new motor skills, pointing to the involvement of different brain regions in skill learning and memory retention.
Mindmap
Keywords
💡Henry Molaison
💡Lobotomy
💡Seizures
💡Medial Temporal Lobe
💡Hippocampus
💡Anterograde Amnesia
💡Memory Researcher
💡Declarative Memory
💡Non-Declarative Memory
💡Motor Skills
💡Ethical Considerations
Highlights
In 1953, Henry Molaison underwent a brain surgery to cure his severe seizures, which led to the discovery of the brain's role in memory formation.
The surgery removed the medial temporal lobe, including the hippocampus, amygdala, and entorrhinal cortex, which resulted in Henry's inability to form new memories.
Despite memory loss, Henry's perception, intellect, language, and motor skills remained unaffected post-surgery.
Henry's case, known as Patient HM, revolutionized the understanding of memory, showing it is localized to specific brain structures.
Brenda Milner's research on Henry revealed that memory is not uniformly distributed throughout the brain but is confined to certain areas.
Henry demonstrated that long-term memories formed before the surgery were intact, indicating a distinction between short-term and long-term memory storage.
Henry's ability to learn new motor skills post-surgery showed the existence of multiple memory systems in the brain.
Memory was categorized into declarative and non-declarative types, with non-declarative memory being linked to structures like the basal ganglia and cerebellum.
Henry's case study highlighted the importance of the medial temporal lobe in creating new memories and the process of memory consolidation.
The preservation of Henry's non-declarative memory after surgery underscored the different neural pathways for various types of memory.
Susanne Corkin continued Brenda Milner's research, further exploring the complexities of Henry's memory and its implications for neuroscience.
The ethical considerations surrounding Henry's case raised questions about the treatment of research subjects and the balance between scientific discovery and personal autonomy.
The controversy over Henry's brain donation and the actions of his conservator and researchers reflect the ongoing debate about ownership and exploitation in scientific research.
Henry's story emphasizes the human side of scientific research and the need to recognize the individual behind the research subject.
The video concludes with a reflection on the legacy of Henry Molaison and the ethical implications of his treatment by the scientific community.
Transcripts
In 1953 a desperate young man agreed to undergo an experimental procedure to
remove a part of his brain in an attempt to cure his seizures Henry Molaison had
begun experiencing seizures as a child following a bicycle accident where he
cracked his skull. At 27 years old his seizures were so severe and
uncontrollable that he was unable to lead a normal life. His surgeon William
Scoville was a well-known lobotomist at the time. He had spent his career
performing lobotomy on psychotic patients and noted that in some of those
patients the lobotomy had the unintended consequence of relieving their seizures.
And so on September 1st 1953 William Scoville removed a thumb-sized section
from both sides of Henry's brain. The majority of the medial temporal lobe was
removed including the hippocampus, amygdala and entorrhinal cortex. The
surgery did alleviate some of Henry's seizures but they also left him unable to
form any new memories, eventually becoming known in the medical literature
as patient HM. Our understanding of memory at the time was rudimentary.
Memory was thought to be distributed throughout the entire brain and tied to
other brain functions such as perception and intellect. But the surgery didn't
affect Henry's perception nor did it dim his intellect, in fact he scored
higher on IQ tests following the surgery. Similarly his language and motor
skills were entirely preserved. It seemed the only thing he had lost was the
ability to form new memories. Two years later in 1955 Henry Molaison was visited
by a memory researcher from McGill University Brenda Milner, who then spent
the next three decades of her career testing and studying Henry's brain -
eventually passing him on to her former student Susanne Corkins.
Though Henry was studied extensively by both Brenda Milner and Suzanne Corkins,
it was Brenda Milner's early observations that taught us most of what
we know about memory. Milner found Henry to be the ideal study subject. He was
highly intelligent well-mannered and could sit through hours and hours of
testing without ever getting bored or complaining, always eager to cooperate. It
was in those early years that we were able to conclude that memory far from
being distributed throughout the entire brain was limited to specific brain
structures, namely the hippocampus and adjacent perirhinal, entorhinal and
parahippocampal cortices; together they are now referred to as the medial
temporal lobe memory system. But Henry's memory loss was an anterograde amnesia
meaning that he was unable to create any new memories while still
being able to recall long-term memories from before the surgery. This is because
while the medial temporal lobe is responsible for creating new memories,
once these memories have been consolidated over time becoming
long-term memories they are then moved to be stored outside the medial temporal
lobe in other parts of the brain. While Henry was able to recall personal events
from his childhood with remarkable clarity and able to recognize the faces
of famous people who were in the news before his surgery, Brenda Milner found
herself having to introduce herself for the very first time every single time
she met him. Milner observed that despite Henry's inability to create any new
memories or remember things he was still able to acquire new motor skills. He was
able to learn new complex skills such as mirror drawing and was able to retain
those skills. This was the earliest demonstration that there existed
multiple memory systems that were housed in different parts of the brain.
Eventually we came to understand memory as being either declarative (the ability
to recall factual information) or non declarative (an umbrella term that
describes skill learning, habit learning and emotional memory - things like walking,
cycling and nail-biting). We now know that non-declarative memory
depends on the basal ganglia, amygdala, cerebellum and neocortex. These
structures were all preserved during Henry's brain surgery in 1953 thus
allowing him to acquire new skills and habits. You probably noticed that
throughout this video I referred to Henry as simply Henry or as Henry
Molaison despite him being known in most of the academic literature as
Patient HM. There are several reasons why I insisted on this. Henry was able to
provide scientists with tremendous insight on the inner workings of the
human brain. Throughout his life scientists like Brenda Milner and
Susanne Corkins built their careers on the back of Henry's mind, but despite the
great debt owed to him Susanne Corkins effectively became Henry's gatekeeper
controlling who was allowed and denied access to him. Eventually she arranged
for a distant third cousin, Thomas Mooney, to become Henry's conservator in 1992.
Soon afterwards, Mooney signed a brain donation form donating Henry's brain to
Susanne Corkins and her team. When Henry died on a cold winter afternoon in 2008
Corkins arranged to have his brain removed from his skull. She claimed
ownership over his brain, his family pictures and all of his belongings. When
she saw his brain through the glass after it had been removed
she later wrote in her diary that she felt absolutely nothing at all except,
"ecstatic." It's clear that to Corkins Henry was not a real person; he was
merely a new discovery, a scientific paper to be published -- Patient HM; an object to
be owned and something to build your career on. Perhaps she forgot the
desperate young man who trusted his life in the hands of an overly enthusiastic
lobotomist, who looked in a mirror many years later
surprised to see his own elderly eyes "I'm not a boy," he'd remark bewildered.
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