Amnesia Patients’ Brain Illuminates how Memory Works

Researchers report that a 3-D brain scan of a man who lived with total amnesia for 55 years could reveal clues about what caused his memory loss and how the memory works. Henry Molaison (often referred to as H.M.) underwent brain surgery for epilepsy in 1953 and then lost the ability to store memories. The surgery was performed in the medial temporal lobe region of the brain, including the hippocampus. A paper published in Nature Communications describes what happened next.



Even though he suffered from memory loss; his language, intellectual skills, personality and perceptual skills remained intact. The extent of his memory loss was very unique and he underwent numerous neurological studies until his death in 2008. The study authors explained in a news release from the University of California, San Diego that his case provided the first conclusive evidence that the hippocampus plays a role in forming new memories.



Then in 2009, led by Jacopo Annese at UCSD, researchers dissected Molaison’s brain and sliced it into 2,401 tissue pieces that were frozen in order. As the brain was being sliced, researchers took digital images that were then used to create a 3-D model. Study authors noted that the 3-D model can offer much more insight into what happened in his brain during the epilepsy surgery and how it affected his memory compared to MRI’s that were taken while he was alive.



“Our goal was to create this 3-D model so we could revisit, by virtual dissection, the original surgical procedure and support retrospective studies by providing clear anatomical verification of the original brain lesion and the pathological state of the [surrounding] areas of H.M.’s brain,” Annese said in the news release. The model has already revealed a small, previously undiscovered wound site in the brain’s left orbitofrontal cortex. It was likely caused during the 1953 surgery, Annese said.






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