The Function of the Hippocampus Shown by Patient H.M.’s Sacrifice

In this video, I discuss the functions of the hippocampus revealed by Henry Molaison, also known as Patient H.M. who underwent a drastic surgery which resulted in the removal and lead to the total destruction of the hippocampus. By removing the hippocampus, scientists were able to finally understand its function in the brain. | Buy some running shoes https://amzn.to/2NuyhJp, because aerobic exercise improves hippocampal function: http://www.pnas.org/content/108/7/3017 | Learn More About the Hippocampus: https://therevisionist.org/reviews/exploring-function-of-hippocampus-by-anatomy/
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Henry Gustav Molaison (February 26, 1926 – December 2, 2008), known widely as H.M., was an American memory disorder patient who had a bilateral medial temporal lobectomy to surgically resect the anterior two thirds of his hippocampi, parahippocampal cortices, entorhinal cortices, piriform cortices, and amygdalae in an attempt to cure his epilepsy. Although the surgery was partially successful in controlling his epilepsy, a severe side effect was that he became unable to form new memories.

Henry Molaison experienced intractable epilepsy that has sometimes been attributed to a bicycle accident at the age of seven. He had partial seizures for many years, and then several tonic-clonic seizures following his 16th birthday. In 1953, he was referred to William Beecher Scoville, a neurosurgeon at Hartford Hospital, for treatment.

Scoville localized Molaison's epilepsy to his left and right medial temporal lobes (MTLs) and suggested surgical resection of the MTLs as a treatment. On September 1, 1953, at the age of 27, Molaison's bilateral medial temporal lobe resection included the removal of the hippocampal formation and adjacent structures, including most of the amygdaloid complex and entorhinal cortex.[9] His hippocampi appeared entirely nonfunctional because the remaining 2 cm of hippocampal tissue appeared to have atrophied and because the entire entorhinal cortex, which forms the major sensory input to the hippocampus, was destroyed. Some of his anterolateral temporal cortex was also destroyed.

After the surgery, which was partially successful in its primary goal of controlling his epilepsy, Molaison developed severe anterograde amnesia: although his working memory and procedural memory were intact, he could not commit new events to his explicit memory. According to some scientists, he was impaired in his ability to form new semantic knowledge,[10] but researchers argue over the extent of this impairment. He also had moderate retrograde amnesia, and could not remember most events in the one- to two-year period before surgery, nor some events up to 11 years before, meaning that his amnesia was temporally graded. However, his ability to form long-term procedural memories was intact; thus he could, for example, learn new motor skills, despite not being able to remember learning them.

When Milner first visited H.M., she saw that the epilepsy was now controlled but that his memory impairment was even more severe than in Penfield’s two patients, P.B. and F.C. What she observed was someone who forgot daily events nearly as fast as they occurred, apparently in the absence of any general intellectual loss or perceptual disorder. He underestimated his own age, apologized for forgetting the names of persons to whom he had just been introduced, and described his state as “like waking from a dream ... every day is alone in itself...” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2649674/
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Picture Credits:
Life Science Databases, via Wikimedia Commons
Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 2002-4436.
Anatomography, via Wikimedia Commons
MistyHora, via Wikimedia Commons

Видео The Function of the Hippocampus Shown by Patient H.M.’s Sacrifice канала Raqib Zaman