HM - the man with no memoryHM - the man with no memory
All In The Mind
The story of HM, the man with no memory and what he taught neuroscience.
28:50•10 Nov 2013
HM: The Man With No Memory and What He Taught Us
Episode Overview
- Henry Molaison’s case showed that severe memory loss can exist alongside above-average intelligence and intact language.
- Removal of the hippocampal region on both sides of the brain was shown to cause lasting amnesia, changing neurosurgical practice.
- His preserved short-term memory and ability to learn motor skills highlighted that different types of memory rely on different brain systems.
- Emotional information is retained more strongly than neutral facts, even in someone with profound memory impairment.
- Despite fragmented past and future awareness, Henry retained a partial sense of self and a strong altruistic wish to help others through research.
“What is found out about me helps you to help others. And I figure that's more important in a way.”
Ever wondered what it takes to lose your memory yet keep your sense of self? This episode of All In The Mind follows Henry Molaison, known for decades in neuroscience circles simply as "HM", whose experimental brain surgery for epilepsy wiped out his ability to form new long-term memories. Through calm, curious conversation, host Lynne Malcolm talks with neuroscientist Suzanne Corkin and neuropsychologist Jenny Ogden, who spent years working with Henry.
You’ll hear Henry’s own voice as he calmly admits, "I don't remember things" and, more movingly, "What is found out about me helps you to help others. And I figure that's more important in a way." The episode focuses on how removing Henry’s hippocampus and most of his amygdala created profound amnesia, yet left his intelligence, language and personality intact.
You’ll get a clear, jargon-light explanation of short-term versus long-term memory, and how Henry’s case reshaped modern memory research, showing that memory is handled by specialised brain circuits rather than being a single, general skill. Corkin explains how Henry could chat warmly, repeat digit strings and learn new motor skills, yet instantly forget people he’d just met or stories he’d just told.
There’s a powerful thread about identity too: even without detailed autobiographical memories or the ability to imagine the future, Henry still showed a partial sense of self, shaped by fragments of past knowledge and an enduring awareness that his memory was "horrible". You’ll also hear about the planning that went into donating and scanning Henry’s brain after his death, and how his case has changed neurosurgical practice worldwide, reducing the risk of others experiencing similar catastrophic memory loss.
For anyone interested in how the brain, memory and identity connect – including those reflecting on how past drinking or substance use may have affected their own memory – this episode offers a humane, absorbing story of science, vulnerability and quiet generosity. What does Henry’s "permanent present tense" say about how much our memories shape who we feel we are?
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