Speaker 1: Welcome to brain Stuff. Production of iHeart Radio, Hey brain Stuff,
Speaker 1: Lauren vogebam here. When the movie Memento came out in
Speaker 1: the year two thousand, audiences were stunned by the unusual storytelling.
Speaker 1: The film centered on a protagonist with no long term memory.
Speaker 1: Every few minutes, he'd forget what he had just learned,
Speaker 1: and to help the audience empathize, director Christopher Nolan had
Speaker 1: the story unfold in reverse chronological order. It gave viewers
Speaker 1: the opportunity to piece together information the same way they
Speaker 1: would if they themselves couldn't retain long term memories, and
Speaker 1: researchers have actually used this effect of this film to
Speaker 1: deepen our overall understanding of the memory mechanisms in the brain.
Speaker 1: One of the study authors said in a statement, Memento
Speaker 1: simulates what it would feel like to be a person
Speaker 1: who has suffered damage to the hippocampus that has obliterated
Speaker 1: the formation of long term memories. Even short term memories
Speaker 1: last only a couple of minutes before they're gone. The
Speaker 1: hippocampus also gets damaged, albeit to a lesser extent in
Speaker 1: cases of severe and protracted stress. A stress hormones gnaw
Speaker 1: the brain brain. Nerds, which honestly should probably be all
Speaker 1: of us, may know that the amygdala plays a major
Speaker 1: role in controlling fear, and the cerebellum makes coordinated movement possible.
Speaker 1: But how does the hippocampus work and why does it
Speaker 1: play such a pivotal role in keeping our memories safe.
Speaker 1: We spoke with psychiatrist Ellen Vora, m d. She explained
Speaker 1: that the hippocampus is quote part of our limbic brain,
Speaker 1: a deep, primitive part of our brain that's associated with
Speaker 1: emotion and memory. The hippocampus in particular is associated with
Speaker 1: consolidation of memory. Located in the temporal lobe. This tiny
Speaker 1: organ plays a massive role in the storage of long
Speaker 1: term memories and the memory of the location of people
Speaker 1: and objects. It's named for the Greek words hippo, meaning
Speaker 1: horse and campo, meaning monster, which is a word for
Speaker 1: sea horse, because the structure curves around like a sea
Speaker 1: horse or horseshoe. We actually have to hippocamp by structures,
Speaker 1: one in each hemisphere of the brain, though together they're
Speaker 1: generally referred to as the singular hippocampus. And yes, the
Speaker 1: hippocampus resides in the limbic system, which is associated with
Speaker 1: emotions and reactions. As you might expect, people with Alzheimer's
Speaker 1: disease have demonstrated damage to the hippocampus. The function of
Speaker 1: the hippocampus is perhaps most clear and examples of patients
Speaker 1: who have stained damage to theirs. In the nineteen fifties,
Speaker 1: scientists William Beecher Scoville and Brandon Milner described what happened
Speaker 1: to a man with epilepsy who had received surgery on
Speaker 1: his hippocampus in an effort to relieve the seizures. He
Speaker 1: retained memories from his childhood, but he couldn't form new
Speaker 1: memories or piece together when or where things happened. That
Speaker 1: same decade, Dr William Scoville began removing patients hippocampus. At
Speaker 1: the time, scientists knew it helped process emotions, but they
Speaker 1: weren't totally clear on how. Scoville wanted to see what
Speaker 1: would happen if he removed part of the brain in
Speaker 1: patients exhibiting certain symptoms like seizures. One such patient, referred
Speaker 1: to as h M, underwent the surgery and found relief
Speaker 1: from his epilepsy, but a near total loss of memory.
Speaker 1: In the nineteen eighties, Kent Cochrane, famously known in the
Speaker 1: psychology and neuroscience worlds as k C, fell off his
Speaker 1: motorcycle and lost several brain structures, including his hippocampus. Predictably,
Speaker 1: he lost most of his memories, but held on to
Speaker 1: some specific ones from his earlier life, all things that
Speaker 1: seemed rooted in fact and devoid of emotion or context.
Speaker 1: Experts later came to call these types of memories sabantic memories.
Speaker 1: So while patients like k C could clearly keep a
Speaker 1: handful of memories intact, most were lost. Recollections of personal
Speaker 1: experience are all pretty much a loss in the damage
Speaker 1: or removal of the hippocampus. These types of memories are
Speaker 1: now known as episodic memory. K C, for example, could
Speaker 1: remember that his brother had gotten married, and he could
Speaker 1: recognize family members in photos from that day, all facts
Speaker 1: based in sabantic memory, but he couldn't remember his family
Speaker 1: reacting to the perm he had gotten for the occasion,
Speaker 1: which is episodic memory. Over time, scientists came to understand
Speaker 1: that the hippocampus is involved in two types of memory,
Speaker 1: declarative and spatial. Declarative memories are the ones associated with
Speaker 1: facts or events. A semantic memory is considered one type
Speaker 1: of declarative memory, and episodic is another type. The hippocampus
Speaker 1: is also involved in spatial relationship memories, the kind related
Speaker 1: to roots and pathways, and it's also where short term
Speaker 1: memories are turned into long term memories, which are then
Speaker 1: stored elsewhere in the brain. Different types of illness and
Speaker 1: accidents can damage the hippocampus, and doctors generally aren't removing
Speaker 1: the hippocampus for experimentation anymore like in the case of
Speaker 1: h M, though Alzheimer's disease is perhaps the most notorious
Speaker 1: destroyer of the hippocampus, as the condition has been correlated
Speaker 1: with atrophy or shrinking of that area of the brain,
Speaker 1: as in the case of HM. Epilepsy is also known
Speaker 1: to affect the hippocampu us. Studies have shown that between
Speaker 1: fifty of patients with epilepsy have hippocampus damage. Two other
Speaker 1: serious threats to the hippocampus, as mentioned above, are severe
Speaker 1: depression and stress. Studies have demonstrated that the hippocampus can
Speaker 1: shrink by up to twenty in people with severe depression,
Speaker 1: and reviews of studies found that people with severe depression
Speaker 1: may have hippocampy that are an average of ten smaller
Speaker 1: than in those people without depression. Vora said, it's a
Speaker 1: part of the brain that's very susceptible to stress. We
Speaker 1: see it lose volume under conditions of chronic stress and depression. Conversely,
Speaker 1: you can restore your hippocampus with meditation and stress management.
Speaker 1: You want a healthy hippocampus so you can remember things.
Speaker 1: Review of studies found that exercise in old age may
Speaker 1: have the ability to help strengthen the hippocampy's ability to
Speaker 1: generate new cells, which could in turn help prevent cognitive decline.
Speaker 1: It's still unclear how and why this works, but researchers
Speaker 1: are continuing to investigate the connection. Seventeen study also found
Speaker 1: the hippocampus may play a role in many more functions
Speaker 1: than memory and path finding. The tiny organ may also
Speaker 1: have a part in enhancing the responsiveness of vision, touch,
Speaker 1: and hearing. Thanks to the continued new findings, some have
Speaker 1: begun referring to the hippocampus as the heart of the brain.
Speaker 1: Today's episode was written by Michell Konstantinovski and produced by
Speaker 1: Tyler Clang, with kind assistance from Dylan Fagan. Brain Stuff
Speaker 1: is production of I Heart Radio's how Stuff Works. For
Speaker 1: more in this and lots of other brainy topics, visit
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