What happens when you remove the hippocampus? - Sam Kean

When Henry Molaison (now widely known as H.M.) cracked his skull in an accident, he began blacking out and having seizures. In an attempt to cure him, daredevil surgeon Dr. William Skoville removed H.M.'s hippocampus. Luckily, the seizures did go away — but so did his long-term memory! Sam Kean walks us through this astonishing medical case, detailing everything H.M. taught us about the brain and memory.

Lesson by Sam Kean, animation by Anton Bogaty.

[Fabian-jhbw]

I once saw a documentary about this man. The saddest thing that sometimes happened to him was that he saw himself in a mirror and that he wouldn't see himself, a young man, but an old man. When he realised he was the old man infront of the mirror he started crying. Fortunately he forgot about that after 15 minutes.

[vickitwiford]

My Dad had Alzheimer's. I took him for rides at least twice a week. We would drive over the same beautiful bridge in one direction, turn around and drive over it from the opposite directions. Both times he would say, "Wow, this is the most beautiful bridge I've ever seen!" Rather than be depressed about his inability to remember he had just seen the bridge, I decided to call it, "The beauty of the first impression!" He was never bored seeing the same thing over-and-over again. It was always fresh and new to him.

[ferdyhoshigakitube]

Thank you H.M you are truly and literally a forgotten hero.

[susanjarman]

His memory died while memory of him lived on

[chakKuR]

He died not knowing what he did for humanity. That's pretty sad :(

[elvisronsamoden]

3:57 *"EVEN THOUGH HE HAD NO MEMORY OF PREVIOUS ATTEMPTS, HIS UNCONCIOUS MOTORS CENTERS REMEMBERED WHAT THE CONCIOUS MIND HAD FORGOTTEN"* that was like a passage from a romantic novel.

[jaysun]

Wow HM lived such a long life without the ability to form memories, I couldn't even imagine how his life would be.

[fancyjosh]

Rest in peace H.M. you did more for mankind than I could ever give.

[haileyxin]

This actually makes me feel sad. What if he had loved someone before the surgery? :(

[faisala.]

"They said dont think about past or future, live in the present"- H.M, 1969.

[PrinNana]

aww I feel bad for him. it's like the meaning of his life was only there to be used

[prftaepps]

He taught us how memories are made by not being able to make his own.

[maralg]

omg, this is amazing. I had 3 brain surgeries & my hippocampus was removed. I do live w/ memory problems daily as well as cognitive. However, I have to keep in mind that I have been SEIZURE FREE since 2011. Thank you for making this video. It's very hard to explain to people. This video makes it a little easier to help people understand. Thnx :)

[eleanorfogarty]

This is incredibly interesting, but I feel so heartbroken for HM. His memory of himself and his life was essentially removed, and he never got to remember most milestones in life, if he made any at all (other than age). I appreciate that there is sometimes seemingly only feasible one way to study something, but the studies of HM feel equally as a scientific breakthrough and a robbery of life. Then again, they did not know most of the crucial role the hippocampus played.

[ShaolinMonkster]

That's sad. I really feel bad for the people that lose their memories :|

[tinycatfriend]

i feel sad for this man, but i'm glad he seemed to have a peaceful life despite the severe memory impairment. we learned so much from him, and we never have to let someone lead a life like that again (at least, not without the patient knowing what the surgery entails).

[AlyssaTaylor]

This is really interesting, but geez, poor guy:/

[amaliaaswin]

Thank you Henry Molaison, you may not realized but you really have a big impact for medical world

[Orikron]

So, he could watch his favourite movie all over again, play his favourite game all over again (without "forgetting" how to play it).

[DinitoThompson]

RIP H.M.

You may not have memories of your own but I and many others do and you will always occupy a spot in ours.

Thank You for your continued approval to further scientific research, True Hero.