Does your Brain diminish certain memories during sleep?
By The Headlines, December 26, 2022 | 05:45 PM
Brain tosses out certain types of memories in order to prevent the overloading of the memory system.
- Scientists have known for years that the brain replays memories and consolidates them during sleep, which helps with long-term memory storage.
- But sleep-related memory replay can also result in memory erosion.
- Scientists studying memory storage recently found a way to explore their technique by using information gained from recent studies.
One of the sleep's many functions is helping you form memories. During those hours, memories that have just been created are reviewed and saved in long-lasting storage. New findings also suggest that sleeping can help with information retention.
Basically, memory is associative in nature. It's reliant on the relationships we make between pairs of unrelated things, or events: When we remember an event, we use fragments of memories and don’t usually recall the event as a whole. For this reason, related memories may be made up of similar fragments which are “overlapping” with each other.
Some researchers have suggested that in slow-wave sleep — the deepest phase of non-rapid eye movement sleep — replay strengthens associations between overlapping memories. Memory is a tricky thing and can change depending on the way it was encoded. A 2017 study found that it strengthens or weakens related memories depending on factors like severe strength of memory, etc.
To investigate this topic more in-depth, Bárður H. Joensen of York University and his colleagues used a technique called targeted memory reactivation to specifically induce the recall of new memories in study participants while they sleep.
Targeted memory reactivation
The research had 30 participants learn a series of 60-word triplets, each consisting of three objects, locations and celebrities. The triplets were actually presented in pairs that included overlapping items, with each word presented alongside a spoken word specific to each triplet. We’ll use David Beckham as an example. If you put in “David Beckham bicycle”, the AI will pair it with “castle bicycle.” The study found that listeners could guess the word “bicycle” from these three words.
Importantly, pairs of stimuli were presented at different intervals in order to manipulate the strength of the association between them. For example: when a subject sees 'car' followed by 'rain', they will be more likely to think of 'weather' after seeing either stimulus. People respond to two images being shown closer together than they do to two that are presented further apart, so you should keep this in mind when you are designing an ad.
The researchers conducted a follow-up test by asking participants to remember some of the word pairs. To trigger something in their memory, they induced recall by playing back words that had been presented with the triplet. Morning, they tested their
They found that overnight memory reactivation increased and decreased participants' retention, depending on whether the first or second-word pair was presented. The participants were much better able to remember the first word pair.
This was only the case for word pairs that were not tested before the participants went to sleep. The test that took place before sleeping consolidated memories of these words, which were then more likely to be remembered later.
Studies show that targeted memory reactivation can lead to improved memory for some word pairs, but also causes forgetting of overlapping pairs that were presented afterwards.
Previous work has shown that memories are easier to recall when your prefrontal cortex is active, but sleeping allows for this activity during memory retrieval. This is the first time this has been seen to happen in a sleep-related study..
The researchers are claiming that this is a way to prevent irrelevant data from consuming your memory, giving you the opportunity to store more and better information.
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