Debunking myths: Reading a scientific article cited in the internet

Purpose of this post

  I was thinking on writing a post about this topic for a while, since I mentioned previously that scientific articles have lots of technical data and are very confusing to read it, since they mention specific techniques and terminologies that most of the people don't know. I remember when I started my academic carrier, we had seminars in which every time one student used to present one scientific paper, and explaining everything. Every figure was debunked, showing the methodology and associating to the written part of the text. It was always a very difficult task. Sometimes a newspaper or any other source of information cite new or old scientific articles, it is always good to check the original source, since sometimes that reading and interpretation of the information misleads to exaggerated conclusions and sometimes even WRONG conclusions. I am currently re-writing this post, I was going to use a very fresh example linked to a post in hive, but I preferred to use a softer example using one regular news in a important news channel in the internet.

The example

  The original article is found at cbc.ca . It describes that spiders have REM-like sleep, something similar to humans. That is going to be interesting. Since it is an article linked to zoology (science that studies animals in general). I am a biologist but I don't read much about zoology or even arachnology for years, so I am a lay in the subject. Let's see if we can go together through this. The article cited by this news was published at PNAS journal, a very well-known journal in sciences. The article came earlier this month and it was published by Rößler and collaborators. So let's see what the news from CBC brought :

In a study published recently by a team of scientists from Germany, Italy and the U.S., researchers reported jumping spiders entering into a REM sleep-like state based on evidence of eye movement and twitching of their limbs... Rößler wondered if the creature was sick — or worse, dying. But further research revealed that the movement happened at regular intervals — which is when she says they started hypothesizing that they were actually experiencing something like REM — or rapid eye movement — sleep.

  So lets open the scientific paper together. The article is open access so anyone can open it. Is it real that they demonstrate that? Or it is just a self-promoting article? We don't need to understand all the figures from the article to reach the same conclusions so let's see some important parts of the article that can help us to check this information.

The text composition of a novel research in a scientific article

  An article is composed by the same structure in every journal, sometimes the journals change the orders and even add some topics like material methods as supplementary files. Usually, you have the title of the text with authors and filiation followed by the abstract of the article. The abstract is a summary, which includes all the topics of the article, it can reach 100-300 words. The main body of the text starts with an Introduction, which the author briefly go through the background of the research area and usually ends with a paragraph about the aim of his research. You will find the Material and Methods after in most of the journals, in which the authors describes every sample that was used, patients or whatever in addition to all scientific methods that helped him to achieve the results, including experiments and statistic calculations. After the background and the description of the methods, you will find the Results, which is a descriptive way to demonstrate what is behind the figures, and graphics that the authors got as an output from their experiments. The debate about the possible implications of the results come in the Discussion (which sometimes is compacted with the results) when new hypothesis is formulated and also compression with other published works. And finally, the article ends with the conclusion, which is a couple of paragraphs re-stating some important concepts already discussed and the references which is very important to check again if a statement in the paper can be really found in previously published works.

Let's open the paper

Screenshot from the paper at pnas.org website

1. Using the abstract

  The abstract already gives some tips about the conclusions and discussion of the paper, so sometimes we can find the information that we want already in the abstract. The only information that it looks like what is mentioned it is found in the conclusion of the abstract:

Here, we report evidence for an REM sleep–like state in a terrestrial invertebrate: periodic bouts of retinal movements coupled with limb twitching and stereotyped leg curling behaviors during nocturnal resting in a jumping spider. Observed retinal movement bouts were consistent, including regular durations and intervals, with both increasing over the course of the night. That these characteristic REM sleep–like behaviors exist in a highly visual, long-diverged lineage further challenges our understanding of this sleep state. Comparisons across such long-diverged lineages likely hold important questions and answers about the visual brain as well as the origin, evolution, and function of REM sleep.

  There are very technical words there but here the authors state that they found something similar to REM state in spyders, with some descriptions about the movements of the limbs and also retinal movements. And this is important for understanding the sleeping evolution. Ok! let's move forward to the main text to see if we find something else.

2. Using the Dicussion and/or Conclusion

  Since here the author usually integrates the results comparing with other published works, it is easy to find some important statements, so here we come:

This report provides direct evidence for an REM sleep–like state in a terrestrial invertebrate—an arthropod—with clear parallels to REM sleep in terrestrial vertebrates. The combination of periodic limb twitches and eye movements during this sleep-like state as well as the increase of duration of REM sleep–like bouts meets core behavioral criteria of REM sleep observed in vertebrates, including humans (2).

  So here the authors state again that they found this pattern associated to REM in spiders (which together with insects and crustaceans are arthropods) which are similar to vertebrates, including humans.

Sleep and REM sleep in particular are mostly studied under laboratory conditions, limiting our understanding of sleep in nature. While difficult, studying sleep in natural settings is particularly important to understand its function. Sleeping animals are vulnerable due to increased arousal thresholds, limiting vigilance and defense (10).

  Interestingly in this paragraph the authors state a limitation of the study, since this was observed in the lab and not in the real nature. So there is a chance that maybe this behavior can't be found in nature and only future works will confirm that.

For example, web-building spiders with poor vision but excellent vibration sensing may activate muscle groups associated with sensing vibrations during sleep as part of consolidating vibratory memory during awake states... Indeed, honeybees display different sleep phases, including an antennal movement phase and a deep sleep phase (with immobile antennae) linked to long-term memory formation ... While sleep is ubiquitous in the animal kingdom, it remains to be demonstrated whether REM-like sleep is equally universal and how these sleep phases may be expressed in less visual species. Conversely, eye movement during REM sleep may be a unique feature of visual brains, with this convergent evolution suggesting some critical vision-specific functionality.

  The last fragments from the text bring an interesting conclusion, so spiders with more sensitive legs, like the ones that build spiders, have their legs as more active during sleep, similar to bees that use their antennal. So animals with poor vision during this REM-like sleep they use other sensorial organs instead of the eyes during this sleep stage and the eye movement would be associated to visual brains like ours. This is an interesting statement in an evolution point of view.

3. Using the Results

  in this case we already found different places of the text about what is stated at the CBC article. But if we couldn't find it we could try to find at the results , which we can find figures, tables and in this specific case lot's of videos like in this twitter from the first author :

https://twitter.com/RoesslerDaniela/status/1556720951773073411

Periodic bouts of retinal movements in spiderlings were clearly visible (Movie S2) with consistent durations (median = 77.13 s, interquartile range (IQR) = 19.65 s, nobs = 330, nsubj = 29) and regular intervals (median = 16.97 min, IQR = 6.56 min, nobs = 260, nsubj = 17).

  So here the authors describe how is the retinal movements with lots of measurements that I don't understand.

Conclusion

  As lay in the area I found everything that was stated in the CBC article, so it looks like that the media vehicle brought a good perspective other research. If you are an arachnologist you can judge the material and methods and the results to see if what they did was enough to prove it, that's what I do with health-related scientific articles. This example was a cool way to show you guys that is possible to go through information and check it, even if it is something that you think that is real by your belief, sometimes our beliefs are WRONG and we start to spread some UNTRUE information. In the end we learned about some REM sleep evolution in animals :)