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