Can our brains process words while we sleep?



Learning by listening to things while you sleep might be a desperate last resort for budding linguists and university students cramming for their finals, but how much can the human brain actually take on board while in a state of unconsciousness?

It is fairly well-established that the brain processes information while we sleep (such as dealing with memories and ‘information of the day’) and can even respond to certain external stimuli (for instance the hypnic jerk is believed by some to be an ancient response evolved by humans to prevent us from falling from trees as we slept).

Now a team of scientists from France and the UK have tried to see whether or not our sleeping brains can process words to the point where they can understand simple meanings of those words.


So, what’s the point?

The human brain is capable of incredible things – the source of music, logic, poorly-written science blogs and language.

In order for language to work our brains need to be able to interpret the meanings of words. While this might seem like an obvious and simple task, you have to remember that individual words come loaded with various connotations and nuances (the word ‘set’ for instance is described on as having 100 separate meanings involving subjects as diverse as surgery, tennis and chickens).

Another level of complexity in meaning is the categorisation of a word:a simple noun such as ‘ball’ could be considered as a ‘toy’, ‘sporting equipment’ or a synonym of ‘sphere’ and can itself be sub-categorised into different types of ball.

In this study, the researchers wanted to see whether the sleeping brain can distinguish between words which are the names of animals and those which aren’t: a simple interpretation of the meaning of those words.

This kind of study could help to shed light on how our brains work and how we process information, as well as helping us to gain a better understanding of sleep – a state in which we spend around one-third of our lives (although it’s probably closer to half for teenagers and blog-writers).

What did they do?

Volunteers were placed in a dark room, each sitting back in reclining chair with their eyes closed and encouraged to drift off to sleep. Each wore an EEG (electroencephalography) cap to monitor brain activity.

While they were drifting off, the participants were played the names of objects, some of which were animals, and instructed to press a button by their left hand if they heard the name of an animal or to press on by their right hand if it was a non-animal.


Movements of the right-hand side of the body are controlled by the left hemisphere of the brain, and vice-versa, meaning that while conscious, the participants’ brains would associate animal-words with activity in the right hemisphere of their brains with non-animals with the left hemisphere.

Words were played at 6 to 9 second intervals and the participants continued to press the buttons as they descended into sweet slumber, and the words continued to be played while they slept. The EEG caps could monitor brain activity to figure out precisely when they fell asleep, but also to see if the right or left hemispheres continued to light up in response to animal or non-animal words, respectively, even though the participants were no longer pressing the buttons.

Did they prove anything?

Weirdly enough, the volunteers’ brains continued to show stimulation in their right hemispheres in response to animal words and the left hemispheres for non-animals. The scientists reckoned that this shows that their brains could still process the words and interpret the meaning of ‘animal’ and ‘non-animal’ even though the participants were asleep.


In a second experiment, volunteers were presented with a list of words, some of which they had been played while awake and unconscious, and some of which had not been played at all. They had to indicate whether or not they thought each word had been played to them.

Generally speaking, ‘participants could distinguish new words presented during wake period… but crucially not from words presented during sleep’. In other words, while the brain is able to linguistically process words during sleep to some extent, the volunteers did not remember them.

So, what does it mean?

This appears to be pretty strong evidence to suggest that the brain can process the meanings of word that we hear during sleep, at least at a fairly simplistic level of understanding, and begs the question: ‘what else can the brain do during sleep?’

It would be incredibly interesting to find out precisely how sophisticated the brain’s functions are, not only during light sleep, but at deeper stages and the highly-active REM stage too.

While the student dream of being able to learn important exam facts while sleeping off an evening of tequila and aftershocks might not have been realised, this study does provide an exciting insight into what our unconscious mind is capable of.

Original article in Current Biology Sep 2014
All images are open-source/Creative Commons licence.Credit: A Ajifo (First); USNARA (Second); S Kouider et al. (Third); C Hope (Fourth)

Text © thisscienceiscrazy. If you want to use any of the writing or images featured in this article, please credit and link back to the original source as described HERE.

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Kouider, S., Andrillon, T., Barbosa, L., Goupil, L., & Bekinschtein, T. (2014). Inducing Task-Relevant Responses to Speech in the Sleeping Brain Current Biology, 24 (18), 2208-2214 DOI: 10.1016/j.cub.2014.08.016


Monkey language, shrimps’ super sight and how beer can make barbecues healthier



British researchers have ‘translated’ the gesture language of a group of wild chimpanzees. They identified 61 different gestures which they claim are used to communicate 19 distinct messages in total. They say this is the first time they have observed that ‘another animal communication system has meaning, not just information (or)… complicated communication, but actual meaningful communication.’ [See video HERE (BBC)].

While chimps use body language, a group of gorillas appear to use smell to communicate. A new study by British and Portuguese scientists suggests that the group’s silverback, named Makumba, smelled differently depending on the social situation. Two (rather unfortunate) smell ‘raters’ scored Makumba’s odour from ‘none’ to ‘extreme’ in various social situations, with his strongest odours coinciding with ‘high intensity’ interactions and often accompanied by loud noises and chest-beating.


From the proboscis to the psyche: Italian scientists reckon that measuring the electrical activity in the scalp (EEGs) can help to predict how susceptible a person is to hypnosis. Hypnosis itself is still something of a mystery, but reading fourth-rate science blogs is a sure-fire way to be sent into a trance-like state.

David Icke once described TV as a ‘mass hypnotist to the global mind‘, but a multinational team of researchers reckon that interactive TV can be of benefit to older people. Their study showed that using interactive TV to engage in ‘cognitive training’ led to improvements in both ‘working memory‘ and ‘executive function‘. These sorts of activities to keep the brain sharp are typically available via computer, but the researchers hoped that for older people who ‘cannot use or afford a computer’, a TV-based system would be something they would be far more comfortable with.

As the peak of summer approaches (at least in the northern hemisphere), sunscreen becomes an essential for people not wishing to be turned into walking sores, but naturally-occurring sunscreens produced by some bacteria are re-purposed by shrimps to augment their vision. The sunscreen chemicals are located just behind the lenses of the shrimps’ eyes and each one absorbs UV light at a very particular frequency, allowing the shrimp to distinguish between different UV ‘colours’. [Read the full TSIC article HERE].


And no summer would be complete without barbecues and beer – and the beer could well be key to making barbecued meat healthier as well as more enjoyable: Research by scientists in Portugal suggests that using a beer marinade can actually reduce the amounts of potentially harmful chemicals in a barbecued pork loin. Char-grilled meat often contains tiny amounts of polycyclic aromatic hydrocarbons (PAHs), some of which have been identified as carcinogens. But beer contains antioxidants, which can prevent the formation of PAHs. After hosting many barbecues (presumably), the scientists concluded that black beer was particularly good at reducing PAH levels in the char-grilled meat. And who said science was hard work? [See video HERE (The Economist)].

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Credit: T Lersch (First); C Segesvári (Second); Chensiyuan (Third)

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WHTI 30.06.14 – Squeezing light, preserving brains and ‘origami’ microscopes made of paper



Can you squeeze light? Apparently at least in the world of quantum mechanics, you can – basically it means the signal of the light when it is measured has ‘surprisingly low noise’ and so can be used in precision measurements and communication. A group of scientists from Germany and Canada have developed a new method to generate squeezed light, which is in some ways similar to noise-cancelling technology in top-end headphones. The light travels through a cavity, carrying natural fluctuations (noise), but the cavity itself is resonated by two lasers, which can be tuned to match (in reverse) the natural fluctuations of the light and minimise them.

origami microscope

But what if you can’t afford sophisticated lasers and light cavities? Well fortunately scientists in the US have developed ‘origami-based paper microscopes’, as an ‘ultra-low-cost’ alternative to conventional microscopes that can be used by ‘schools and universities’ as well as by ‘amateur microscopists’. The ‘Foldscope’ comes with a range of attachments that allow it to carry out a variety of microscopy techniques, including fluorescence and dark-field (see picture above). [See a video of the Foldscope HERE].

The DIY approach has also been applied by a team of Indian scientists, who have turned silkworm cocoons into batteries using aluminium foil, copper wire and glue. The cocoon walls provide a porous matrix for charged particles to travel through, allowing an electrical circuit to be completed and the batteries are capable of lighting small LEDs. [Read the full TSIC article HERE].

silkworm cocoon batteries

Do musicians brains work differently from other people’s? Scientists have assessed small groups of musicians and non-musicians in a variety of ‘executive function’ cognitive tasks, and in almost all areas, the musicians came out on top. When they scanned the brains of children as they performed one of the tasks, they could see several regions of the brain associated with executive function were more active in the musicians than in the non-musicians.

And finally, in much more gruesome brain-related news, Australian scientists have developed a machine that can help keep a slice of brain alive for over a day. Brain slices are an important resource to help researchers to understand how small sections of the brain work, and this technique uses UV light to control populations of bacteria that will otherwise damage the vulnerable brain cells. [Read the full TSIC article HERE].

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Credit: J Keyser (First); J S Cybulski et al. (Second);
B Tulachan et al. (Third)

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WHTI 15.06.14: Mystery sea monster kills great white shark, trees fighting climate change and why urine might be valuable



We start this edition with what should be top news in Japan – the discovery of Gozilla! Not really, but scientists in Australia reckon a Great White shark – hitherto the ocean’s most fearsome predator has been eaten by an even bigger mystery ‘sea monster’. Spooky. The shark’s electronic tag indicated that it suddenly plunged down nearly 600m and its temperature rose rapidly, indicating that it had been pulled down and then entered the digestive system of another animal. Giant octopus perhaps?

The governments of the world may be dragging their collective heels over climate change, but trees may be helping to reduce the problem. A study by Chinese and Japanese scientists has found that Japanese forests have actually seen a boost in growth due to elevated CO2, extra nitrogen deposition and climate change. All this extra growth means that more CO2 is being removed from the atmosphere and sequestered (trapped) in the biomass of the trees.


But there is good news in the world of recycling: Korean scientists reckon that highly porous mineral carbon, useful for industrial applications such as fuel-cell catalysis, can be produced cheaply be recycling… human urine! It turns out that we could well be flushing away liquid gold as the ‘Urine-Carbon (URC)’ also contains atoms of other elements such as oxygen and phosphorus which would normally be difficult and expensive to ‘dope’ into the porous carbon structure.

To many people (particularly Westerners), traditional Chinese medicine as seen as a hocus-pocus justification for killing tigers. But some (thankfully, herb-based) Chinese medicines have now been shown to have similar effects as tried-and-tested antidepressants. Chinese scientists found that the 7 medicines tested each contained a plethora of biochemicals known to play a role in brain-signalling which could explain why they worked and could potentially help in the discovery of naturally-occurring compounds for use in medicine.


But even without medicine our bodies are pretty adept at looking after themselves. German scientists have discovered how some immune ‘memory’ cells lie dormant in our bone marrow after fighting off a disease (or reacting to a vaccine). They say these cells constitute a ‘long-term memory’ of diseases within our body so we can fight them off more easily the next time they appear. [Read full TSIC article HERE].

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Credit: T Goss (First); Tenzinx3 (Second); NIAID/NIH (Third).
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How UV light can help to keep a brain slice alive



Jar? Check. Pickled brine? Check. Slice of brain? Ch… what?

It might sound like something out of a cheesy sci-fi B-movie (or indeed a Steve Martin comedy classic), but keeping brains alive is an important business for some real scientists, not just Dr Frankensteins.

A team of scientists from Australia have come up with a new technique that can keep slices of rat brain alive for up to 3 days – using UV light and a cooler.

So, what’s the point?

While brain slices may sound like something Hannibal Lecter would put in his sandwiches, they are actually an important tool in studying how the brain works.

If thin slivers of grey matter (known as acute slices) are removed from the rest of the body, it allows small clusters of brain cells to be experimented on in a tightly-controlled environment without interference from other bodily processes. It also allows microscope images to be taken that would be difficult of impossible if the brain was whole.

The method does have its drawbacks: the animal providing the sample must of course be ‘sacrificed’ (meaning euthanised, rather than killed as an offering to mighty Zeus), and the isolated brain sections will not be subject to normal biochemical and electrical stimuli and so may react differently to how it would in the body.

Nevertheless, it it a technique that has arguably led to important advancements in the understanding of brain functions and the ‘molecular and cellular machinery that is defective’ in a number of neuropsychiatric diseases.


However, an important limitation in the use of brain slices is that they age and die quickly – typically within 6-12 hours. Keeping slices alive for longer will mean that a broader range of experiments can be performed on them, and better data can potentially be obtained (since the cells degrade more slowly).

It could also mean that more data can be obtained from each slice, so fewer animals need be killed. This is an important consideration ethically (yes, some scientists do actually have morals), and in terms of cost – both to time and to money.

What did they do?

Brain slices are typically stored in a liquid (or ‘incubated in a medium’ in science lingo). Typically, the medium contains food (glucose) and oxygen in order to help keep the cells alive for as long as possible.

But the researchers reckoned that bacteria could be responsible for cell death too. Unfortunately, while the medium is essential for keeping the brain cells alive, it is also an environment in which bacteria will thrive. The poor brain cells are almost defenceless against the bacteria (because they’re no longer hooked up to the rat’s main immune system), with only some glial cells able to fight them off.

So they researchers looked for ways to control the bacterial population. They ruled out antibiotics, since they could also effect responses in the brain cells and therefore potentially compromise experiments.

Instead, they used an ultraviolet (UV) light to hinder the growth of the bacteria. UV light at a particular wavelength (254nm) can damage DNA (by breaking double bonds in thymine residues, forming dimers). This disrupts the bacteria’s reproductive and cellular processes, hindering their ability to survive and multiply.

However, while microorganisms are more susceptible to UV damage than humans, exposing the brain slice to the UV would likely cause damage to the brain cells too.

To get around this, the scientists came up with a clever solution: They built an incubator (brilliantly named the ‘braincubator’) consisting of two chambers. The brain slices were kept in one chamber and the UV lamp in the other, but the medium was circulated between the two.

This means that the bacteria (most of which are expected to be floating around in the medium) will be exposed to the UV light periodically, while the brain slices remain shielded from it.


They then kept brain slices in their ‘braincubator’ to see how long they lasted compared to slices in a regular (control) chamber. They added a fluorescent marker that indicates the presence of dead cells (it actually binds to nucleic acids, but is generally excluded from living cells by their membranes). They also counted the number of bacteria in samples of both brain slice and medium.

The scientists also cooled the medium in the ‘brainculator’ to 15-16oC. Both bacterial and brain cell metabolism would be expected to slow down at lower temperatures, extending the lifespan of the brain slices. The control was kept at room temperature (~22oC).

Did they prove anything?

They observed little difference in cell survival rates between the two sets of samples after 1 hour (~73%), but after this time the cells in the control sample began to die off quicker than the ‘braincubator’ cells.

After 24 hours, the proportion of living cells in the control had dropped below 20%, while in the ‘braincubator, it remained over 40%. After 36 hours only around 5% of the control sample cells remained viable, while around 30% of the ‘brainculator’ cells were still alive and kicking.

The scientists also found that the concentration of bacteria in both the medium and the brain slices were different too, with the gap also widened with time. After 36 hours there was over 20 times the concentration of bacteria in the control slices compared to the ‘braincubator’ slices. In the medium, the control had around 50 times the concentration of bacteria than the ‘braincubator’.

dead vs alive

So, what does it mean?

The ‘braincubator’ improved the survival rates of the cells in the brain slices, which is ultimately what the researchers set out to do. The fact that as the bacterial population went up, the brain cell count went down, lends weight to the idea that controlling bacterial growth was the reason for the ‘braincubator’s success.

One criticism that can be levelled at this study is that while they proved that a combination of UV-exposure and cooling of the medium prolonged the survival of the cells in the slices, it is impossible to say how much of an influence each of these factors has.

It would have been relatively simple to conduct a parallel experiment where either the ‘brainculator’ was used at room temperature (UV only) or where brain slices were incubated at lower temperature but no UV (low temperature only). This would allow the relative effectiveness of UV and low temperature to be told apart from one another.

Of course, limited time and resources may be legitimate reasons for not conducting a further experiment and may well be an area of future study.

But essentially the experiment appears to have been a success and the ‘braincubator’ is a clever solution to the problem of bacteria in the sample. Similar devices could also be used in other experiments where bacteria are a problem so it could make a difference in other fields of study too.


Not all scientists keep brains in jars, but for those that do the ‘brainculator’ could well prove to be a useful piece of technology for their plans, diabolical or otherwise.

Original article in Scientific Reports Jun 2014

All images are open-source/Creative Commons licence.
Credit: Marvin 101 (First); G Lee (Second); Edited from
Y Buskila et al. (Third and Fourth); J.J et al. (Fifth)

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