Going to travel down a non-biochemistry related path again today, as its the weekend and my weekend reading usually leads me to other fields (too much of any one topic can get boring after all). So I will try my best to be informative and entertaining, and hopefully we can learn something together!

<center>http://i.imgsafe.org/8762ab85a3.png</center>

This post describes work published February 17th 2017 in the journal [Nature: Scientific Reports titled "Sleep Supports the Slow Abstraction of Gist from Visual Perceptual Memories"](http://www.nature.com/articles/srep42950). 



In this work the authors discuss/tested how sleeping helps us form memories in the form of abstract representations, aka the "gist" (pronounced like it were spelled Jist), of the situation we are trying to remember.

<center>http://i.giphy.com/Ppk0LL1mCFa36.gif</center>
<center>These kids are just trying to remember the gist of what it was like to swing at the park</center>

# Sleeping And Memory Formation

The function of sleep and the consolidation of memories in our brains has been studied for quite some time, and is becoming much more well understood. <sup>[[2](http://physrev.physiology.org/content/93/2/681)]</sup> However our memories are not like photographs, our brain does not store an exact snapshot of prior events (which is a fact that may surprise some of you, what you and I remember is likely not EXACTLY what really happened).<sup>[[3](http://www.annualreviews.org/doi/10.1146/annurev.psych.49.1.289)]</sup> The ways our brains store information in the form of memories is much more malleable then an a static image, it can change and become distorted, even to the point where what we are remembering shares no true similarities with the factual occurrence of the past.

Short term memories are usually very vivid, full of a ton of information and details about what ever it is we are remembering, however as time goes on, and the memory becomes a long term one, the details are lost and things become much much more abstract.<sup>[[4](http://journal.frontiersin.org/article/10.3389/fnbeh.2013.00107/full)]</sup>

The abstract form of a memory is called a "gist" and the authors discuss a technique that people have used to study it called the Deese-Roediger-McDermott paradigm. <sup>[[5](http://psycnet.apa.org/journals/xge/58/1/17/)]</sup> This is a method that researchers have done which results in subjects remembering words from lists that were not actually included in them. The example provided in this article was this series of words:

- white
- night
- cat
- dark

Where the "gist" word that people would remember is **Black.** Previous studies on the effects of sleep and the formation of "gist" memories by this technique have not shown any conclusive link (some showed a positive correlation, and others nothing). However all previous studies had tested participants immediately after sleeping, and the authors of this study thought that perhaps a longer period of time was necessary for analysis of the effect of sleep on the formation of these "gist" memories.

# The Study

- Initially 28 participants were assigned to one of two groups a "short term"  group (retention time after 20 mins) or a long term group (retention time after 10 hours), and were shown shapes.
- a morning sub-group and a night time sub-group was used for both the short term and long term groups to control for the effect that circadian rhythm would have on memory formation.
- For the 10 hour long term participants, they were shown the shapes and either allowed to sleep for 10 hours or had to stay awake for 10 hours.
- After the initial re-call tests at the defined time participants waited one year and were tested again.

<center> http://i.imgsafe.org/87e21db96e.png </center>

# Some Findings

<center>http://i.imgsafe.org/87f18d0427.png</center>

So here we are seeing some plots of what the people remembered. In the figure the "prototype" shapes were the "gist" shape a participant was supposed to remember from a series of abstract shapes they were shown, while "high confidence old shapes" are more standard shapes that they would recognize.

What we see is that in the initial test both groups remembered the "gist" shapes equally well, but for remembering the high confidence shapes, those who were shown the shapes and then allowed to sleep for 10 hours remembered them the best. Showing (as a positive control of sorts) that sleep helps in the formation of memories, but "gist" memory is not effected on this sort of time scale.

<center>http://i.giphy.com/7FfUhvnmzsgow.gif</center>
<center>Did these experiments fall flat on their face?</center>

## Nope, They Didnt! Things Get Interesting When We Wait One Year

<center>![](https://steemitimages.com/DQmUd3iM1Y8SDV387Bhyp9pJMB8W3FQQgnzYX8wVNr82m94/image.png)</center>

So here we see the recall of the "long term" participants after one years time. The ability of these participants to remember the "gist" shape is significantly better for those who slept for the 10 hours after viewing the shapes, then for those who did not (p < 0.001 so it's statistically relevant). While the same trend is not seen for the high confidence old shapes. This indicates that for formation of those abstract "gist" memories is in fact aided by sleeping, but that the formation of the memories does not occur, or at least is not solidified until much later.

Basically, previous studies looking at the formation of these sorts of memories were just now allowing for a long enough viewing window to see the effect that sleep had on their formation.

# TL;DR

Sleep has been known to help us form and store memories, however it was not thought to be important for the formation of very long term abstract memories based on a multitude of previous data. This publication shows fairly conclusively that the correlation between sleep and the formation of these memories was just missed in the prior studies do to experimental design that just did not examine the participants over a long enough time frame.

# Sources

1) http://www.nature.com/articles/srep42950
2) http://physrev.physiology.org/content/93/2/681
3) http://www.annualreviews.org/doi/10.1146/annurev.psych.49.1.289
4) http://journal.frontiersin.org/article/10.3389/fnbeh.2013.00107/full
5) http://psycnet.apa.org/journals/xge/58/1/17/

**All Non Cited Images Are From Pixabay.com And Are Available Under Creative Commons Licenses**
**Any Gifs Are From Giphy.com and Are Also Available for Use Under Creative Commons Licences**

**Articles published in Nature: Scientific Reports Are Available For Re-use Under A Creative Commons License**

<hr>
</br>
If you like my work, please consider giving me a follow: @justtryme90. I am a PhD holding biochemist with a love for science. My future science blog posts will cover a range of topics in the biology/chemistry fields.

Thank you for your continued support of my work! I appreciate all those who follow me (and those who don't too).