Mariam Nusrat Khan, X, The Blossoms School, Aligarh

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   One of the most perplexing wonders of nature is the human brain itself. Most of what we know of it today has been discovered by studying live cases of people in which their brains had been affected by an external source. One of the most popular of these is the case of the famous amnesiac Henry Molaison. Henry had been suffering from epileptic seizures since childhood, because of an accident which had caused his skull to crack. At the age of 27, he met Dr. William Scoville, one of the most renowned neurosurgeons of the time. He determined that the seizures were caused by an excess of calcium in the brain, because of glutamate, a substance generated by the hippocampus. Two holes were drilled in the front of Henry's skull, and his hippocampus was sucked out through a metal tube. The procedure was a doubtful one, but it did succeed in getting rid of the seizures.

   However, something else happened too. The surgery was followed by a memory impairment, the studies of which led to one of the most significant turning points in brain research. Back in the 1950's, neuroscientists only had roughly formed ideas about the functions of each part of the brain, and how they interacted with each other. Most of what was known was only by the study of patients who survived brain injuries. That also meant, that there was a very fine line between research and medical practice on the human brain. After the surgery, Henry suffered from severe anterograde amnesia. Anterograde amnesia is the inability to create and store new memories. At the time, it was not known that the hippocampus played a major role in memory. His new condition fascinated scientists and he was widely studied from late 1957 until his death in 2008, popularly known as “Patient HM”. Henry still possessed some memory of his life before the surgery.

   After the surgery, he woke up each day to meet the same people, yet did not remember meeting them. He greeted his doctors like he would have just met them, unable to recall anything beyond thirty seconds. "I've known Henry since 1962, and he still doesn't know who I am, noted Suzanne Corkin, PhD, a long-time researcher who directed the research". His memory never developed after the surgery, and he behaved like a 27 year old all his life. He was always trapped in the moment. This way, scientists came to know that the brain organized memories into short term and long term ones. During his study, Henry was given tests, like tracing shapes from their mirror images or doing crossword puzzles. He could not remember these tests, yet he would improve at them. Henry learnt to use a walker, which suggested that he could in fact remember what his conscious mind forgot. Evidently, the making of these non - conscious memories relied on different neural structures than the hippocampus. Long term memories were thus divided into implicit (non-conscious) and explicit (conscious). Thanks to his studies, the concept of sematic and episodic memories was also introduced.

   After his surgery, Henry could not remember most details of the unique events of his life (episodic memory) but could remember general knowledge of the world (sematic memory). The removal of the tissue left Henry devoid of autobiographic memories, which suggested that episodic and sematic memory were distinct. Henry died aged 82 on December 2, 2008. His name was made public, and his brain was donated to Mass. General and MIT. It was kept at University of California, San Diego, and cut into 70 micron slices in 2009. The brain atlas constructed was made public in 2014. Henry's case has had a major role in the discovery of most of what is known about memory organization. His legacy still continues, as his case has since inspired hundreds of other researchers to use different approaches to investigate amnesia and memory disorders.

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