How memory works

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How memory works

The Conversation

By Jee Hyun Kim and Wes Mountain

Illustrated comic title: "Dr Jee Hyun Kim in How Memory Works. A Conversation comic explainer"
Illustration of a girl tumbling down stars. Narrator: "For many years of my childhood, I had a recurring dream about falling down stairs and hitting my head. Years later my mother told me, 'oh, that actually happened when you were super duper tiny!'"
Narrator: "So was I remembering it? Or was it a dream? And what exactly is memory?"
Illustration of the narrator leaving a house and walking down a path. Narrator: "People often define memory as 'something you can remember', but that's kind of circular."
Illustration of the narrator on a therapist's couch. Narrator: "Freud was the first to theorise that memories we can't consciously remember may still exert control over us through our subconsious. And whild much of Freud's methodology is now criticised, he was on to something with the idea that past events can influence us, regardless of our awareness of them." Freud: "Tell me abour your mother..." Narrator: "Not now."
Illustration of Narrator pondering. Narrator: "So, given that, I would define memory as 'a past that has become part of me'. Hang on... did I lock the door?"
Illustration of the narrator standing between two door locks, one of which has a key inserted. Narrator: "I can't remember because I wasn't paying attention. Attention is critical for initiating memory information."
Illustration of the narrator looking through their purse. Narrator: "We often don't pay attention during simple tasks like turning off the oven, locking the house or throwing things in a bag on our way to work. Did I even grab my keys?"
Illustration of narrator looking at a notification from the Snapchat app on their phone. Narrator: "But attention leads to working memory. Working memory can last from seconds to minutes, but generally only lasts as long as we're directly thinking about it."
Illustrations of a camera and a file containing photos, labelled 'memories'. Narrator: "We know that working memory generally gets worse with age, and that fatigue and drugs impair it. Other than that we actually know very little about how it works. But we do know quite a lot about the processes involved in developing short and long term memory."
Illustration of neurons in the brain talking to each other over tin cans. Narrator: "Short term memories form when two neurons that don't normally talk to each other make a connection. That connection means they can more easily talk to each other again, creating a path to pass chemicals and electricity to each other. We call this ability 'potentiation' - it's an enhanced propensity to be activated through that connection."
Illustration of a metaphorical street map of memories containing street names such as 'study alley' and 'high school bullying road'. Narrator: "The longer the potentiation, the more proteins form into physical connections. And that's how long term memories are formed. While short-term memories may last for just hours, long term memories show actual physical changes as neurons branch to creat neural pathways. Emotion plays a big role in how we recall and reinforce these pathways."
Illustration of the narrator riding a bike. Narrator: "Most of the time when we think about memory, we're thinking about people and events: that's episodic memory. But we also have procedural memory. It's used for knowing how to do things... when I ride a bike, it reminds me how to coordinate my limbs, perceptions and balance based on my memory of previous bike rides. Remembering that gears are used to chainge wheel rotation cincumference? That's semantic memory, which is for learned facts and concepts."
Illustration of the narrator holding a key. Narrator: "But they all need attention. That's the key."
Illustration of an anthropomorphised brain wearing a sweat band and lifting weights. Narrator: "And just like we can improve our bodies with exercise, we can also improve our memory by exercising our brains."
Illustration of the anthropomorphised brain posing with Usain Bolt. Narrator: "And just like how with pyhsical exercise there are people who seem born with a genetic propensity for greatness. Some people appear to have a special ability referred to as eidetic (or 'photographic') memory - they can recall images, sounds etc. with extreme precision."
Illustration of Stephen Wiltshire drawing. Narrator: "The artist Stephen Wiltshire for instance, draws and paints cityscapes based on brief flyovers. In 2001 he drew an accurate, perfectly scaled four square mule area of London a few hours after a single helicopter flyover. It took five days and is 4 metres long."
Illustration of th enarrator looking at a collection of photographs. Narrator: "But does pure eidetic or photographic memory really exist? Probably not... or at least not in the way we think of it - perfect photographic recall of every moment in someone's life."
Illustration of Solomon Shereshevsky picturing a series of objects on a path. Narrator: "Like any other type of memory, eidetic memory is affected by attention, duration and frequency, and reinforced by menemonic devices. The Russian mnemonist Solomon Shereshevsky could recall rendom strings of words sometimes decades later. When asked, he said he visualised laying the objects along a familiar stretch of road while learning them."
Illustration of the narrator racing Bolt, as Shereshevsky watches. Narrator: "It is interesting that compared to physical abilities, we seem to see mental abilities as particularly extraordinary. For instance, we don't really care about how Usain Bolt runs, we just know he's much faster than us. But we study people with eidetic memory extensively to try to understand how they're different to us."
Illustration of the narrator using a brain training app on a tablet computer. Narrator: "So what about brain training apps Can they improve our ability to retain information, and shift and focus our attention? Unfortunately while people can get quite good at the tasks within the app..."
Illustration of a games console controller and the narrator dressed as soldier, with an inequality sign separating them. Narrator: "...there's actually no evidence we retain or develop those skills outside of it. It's just like how becoming incredibly good at first-person shooter games won't make me a real world soldier. They're different skills."
Illustration of the narrator being overwhelmed by notifications from apps on their phone and computers. Narrator: "And the way most modern technology is built means that we're only training our ability to switch attention, not maintain and focus it. Both abilities are extremely important, especially when thinking about how we've evolved to survive. But focusing attention is the most important in terms of forming long-term memory."
Illustration of the narrator placed on a timeline, with their childhood stairs memory in the past and a potential Nobel prize in the future. Narrator: "That's one of the reasons mindfulness practices work. Mindfulness is really all about paying attention. And mindfulness training has been shown to enhance the pre-frontal cortical network, which we know is important in forming memory."
Illustration of the narrator holding a tablet, sitting on a therapist's couch and thinking about the preceding comic panels. Narrator: So if attention is so important to memory, maybe we should be careful about what we focus our attention on. While you may be able to train your brain to do more mechanical memorising and tasks, I wonder what creative thinking you compromise by devoting attention to that. Especially when we have tools like Google and smartphones at our finger tips."

Jee Hyun Kim is head of the Developmental Psychobiology Lab at the Florey Institute of Neuroscience and Mental Health. Wes Mountain is the Deputy Multimedia Editor at The Conversation.

Originally published in The Conversation.