On July 19th, 2018 we learned about

Without climate control, heat waves take a measurable toll on our cognitive abilities

On the hottest days of summer, I generally just feel like giving up. By later afternoon, temperatures in my older building easily surpass whatever’s happening outside, a factor compounded by the outdated myth that “nobody needs an air conditioner in northern California.” The net effect is a feeling of tired fogginess, making concentration on just about any task rather difficult. While this may sound like a lot of whining (it is!) scientists have actually been able to quantify the cognitive hit inflicted by seasonal spikes in heat, pointing out that they take a measurable toll on all of us.

Testing the effects of living in high temperatures

Unusually high temperatures associated with heat waves have long been known to be detrimental to human health, although most research on heat has focused on cases when it’s literally a danger to people’s lives. To investigate cognitive issues possibly experienced by everyone, researchers purposely skipped at-risk populations like infants and the elderly, working only with healthy college students. In theory, any issue that would affect a 22-year-old would probably be an issue for 30- and 40-year-olds as well. The only other criteria that mattered was whether or not each student had air-conditioning in the dormitory where they lived.

Every day of the study, test participants were asked to take a few cognitive tests when they woke up in the morning. The tests included tasks like quickly reading the names of colors with letters displayed in conflicting hues, which is a long-standing way to asses how well someone can filter relevant information in a hurry. They were also asked to do some math and memory tests, giving researchers a range of performance metrics to compare. To make sure environmental conditions were also comparable, test subjects’ rooms were outfitted with temperature, carbon dioxide, humidity and noise sensors. Physical activity and sleep were also tracked with a wearable device.

Extra time and additional errors

After five days of normal temperatures, there was a spike in the area’s heat index. Almost immediately, students living without air conditioning started showing a decrease in cognitive performance. They took 13.4 percent longer in deciphering the color words, and also had 13.3 percent more errors in their math tests. Even after the heatwave broke and the outside world returned to normal, much of that heat was retained indoors, extending the impact of overheated students’ low scores.

Anyone who has lived through unusually hot days won’t be surprised by this, but anecdotally hot homes don’t help science diagnose health problems shape policy. By measuring the significant impact heat has one people’s ability to handle cognitive tasks, this study reveals that rising global temperatures may be causing more immediate and widespread problems than people realized. It’s practical to demand air conditioning for every hot home on the planet, but we may need to further prioritize heat-shedding designs in future construction, plus look for ways to mitigate possible problems caused by people too hot to think clearly.

Source: Extreme heat and reduced cognitive performance in adults in non-air-conditioned buildings by Harvard T.H. Chan School of Public Health, Medical Xpress

On June 25th, 2018 we learned about

Our brains reward learning unless we expect the news to be negative

As far as your brain is concerned, this article may be the neurological equivalent of a pastry or lollipop. It’s not that reading these words will tickle your taste-buds, but if you learn something the same reward centers in your brain that give you the sensation of ‘enjoyment’ when eating sugary snacks will be activated. With an incentive like this, it’s hard to imagine then why people ever thought that ignorance could be “bliss,” since we’d be cheating ourselves out of a bit positive neurological feedback by avoiding new information. Why isn’t all news apparently worth knowing?

Nobody likes learning about losing the lottery

To try to figure out when people do and do not enjoy obtaining new information, researchers invited 62 volunteers how much they wanted to know about a laboratory-controlled lottery. Every participant had a chance to win this experimental game, and they were also informed if the odds were good or bad for that particular round of the lottery. The key to the experiment was how people responded to a chance to learn more about each lottery. Most participants were more interested in hearing news about a lottery they thought they had a chance of winning, turning down information about rounds with worse odds.

A little over half of these participants also had their brain activity scanned so that researchers could look for differences in how key anatomy responded while these choices were made. When a participant thought they’d be hearing good news, agreeing to hear more about a lottery correlated with an increase in activity in the nucleus accumbens and ventral tegmental areas of the brain. When bad news was more likely, these areas did not respond, essentially removing some motivation to obtain new information.

Enjoyment based on expectations

So if people like to pursue good news because it feels good, we also seem to lack a motivation to hear bad news, even beyond the ramifications of the news itself. Indeed, brain scans found that the reward-center activity was largely tied to people’s expectations about the lottery news, and was independent of later reactions to news about actually winning or losing the lottery. This kind of feedback may help explain why people seem to illogically avoid receiving negative but helpful information, such as a diagnosis from a doctor about an ailment. Obviously there will always be bad news in the world, but it seems that shaping our expectations may help it feel pleasant enough to enjoy hearing about.

Source: How your brain decides between knowledge and ignorance, EurekAlert!

On June 12th, 2018 we learned about

Students do better in school when they get frequent breaks from extended instruction

One of the best ways to help kids get more out of their time in the classroom is to spend less of that time teaching. A series of 45-minute lessons broken up by 15-minute recesses seems to have a great effect students’ concentration, enabling greater student engagement for each segment of the day. At first glance, it may sound like a ridiculous amount of time spent out on the playground, but schools in Finland, controlled studies and pilot programs in the United State all suggest that expecting kids to stay focused for hours at a time may not be worth the trouble.

Giving brains a break

In Finland, elementary students are given 15 minutes after each 45-minute lesson to head outside and take whatever kind of break they need. When the students return to the classroom, they’re generally ready to take on the next lesson without much hesitation or time spent getting everyone back on track. Because these recesses are outdoors in rain or shine, it was originally assumed that the physical activity involved was the secret to student’s concentration- that they were essentially getting their wiggles out before taking on a new task. However, experiments in classrooms in the United States found that physical exertion might not be necessary, as even breaks inside the classroom made a difference in student performance.

The key mechanic seems to be more closely tied to how our brains learn and retain new information. If running around a playground isn’t strictly necessary, it seems that simply taking a break from learning is. Various durations of lesson-time have been tested, and 45 minutes seems to be the most students can handle before their brains are essentially full. By having a short time for less-structured thought, students seem to be able to process and remember new information more easily. This mirrors the benefits of taking a nap or getting a good night’s sleep to better retain information.

Aerobics for academics

This isn’t to say that kids don’t benefit from moving around during their breaks. A separate study has found that kids with better physical fitness had more gray matter in their brains. What’s more, this increased brain volume correlated with better academic performance in school, particularly with language tasks. In particular, cortical and sub-cortical regions of the brain were larger in kids with better aerobic and motor function, although it’s not clear what mechanism is driving this boost.

In an era when American education is very concerned with test scores, rigor and notions of personal “grit,” giving kids a recess every 45 minutes may seem like a step in the wrong direction (if you choose to ignore the improved scores and behavior.) However, it may be that elementary schools adopting this schedule are simply falling in line with the adult world. Meetings, college lectures and even television shows are mostly expected to require around an hour of concentration, so really we just need to let our younger kids sync up with the demanding schedules adults make for themselves.

My third-grader asked: How long is a school day in Finland? Do they go to school all year?

While it might be intuitive for Finnish kids to make up their “lost” break time in other ways throughout the year, they don’t seem to worry about it. Schools generally start between 8:00 and 9:00 am, getting out between 1:00 to 2:00 pm. Finns also get summer and Christmas holidays, going to school around the same number of days as many American schools.  The important twist is that this schedule with only 25 hours of instruction a week seems to work really well, as Finish schools are considered to be some of the best in the world.

Source: How Kids Learn Better By Taking Frequent Breaks Throughout The Day by Timothy D. Walker, Mind/Shift

On May 27th, 2018 we learned about

Our memories and imagination may make nouns the most mentally demanding part of speech

Some things are hard to say, but according to an easily quantifiable metric, “I’m sorry” and “I love you” are easy. While there may be emotional difficulties and sharing one’s feelings, none of those words are all that difficult, because non of them are common nouns. A study of human speech across nine languages from around the world has found that all humans are most likely to show a bit of cognitive strain when trying to say the names of specific nouns more than any other part of speech. In a weird way, the issue might come down to our brain’s attempt to familiarize ourselves with what we’re saying before we say it.

The study analyzed recorded conversations from Mexico, Siberia, the Himalayas, the Amazon and the Kalahari Desert. While the specific grammar and vocabulary of these languages obviously differed, a commonality turned out to be how much people hesitate before saying a noun in the middle of a sentence. No matter if someone paused silently or with an “uh” or “um,” they were 60 percent more likely to take an extra moment before saying a noun than a verb. Even difficult or unfamiliar verbs weren’t this likely to require a pause, suggesting that there was something about how a noun is handled in the brain that makes us take an extra moment.

Stopping to see what we’re saying

Researchers suspect that these pauses may be due to our brains trying to conceptualize nouns as we try to say them. When we think of something, our brain brings that information into our working memory, often “seeing” it in our mind’s eye. So when we say “dog,” our brain will give us at least an abstract image of a dog, and that moment of internal observation may cost us enough time that we will need to break the rhythm of a spoken statement. As further evidence of the extra effort nouns require, researchers point out that we often avoid restating actual nouns in spoken conversation, replacing them with pronouns like “it” and “that” as much as possible. Verbs apparently aren’t so taxing, as we they don’t cause us to pause, even if we have to keep explicitly using a verb over and over.

Some of this may be eventually confirmed by observing the brain activity of people during casual conversations, looking at how much one’s own speech activates your memory and visual cortex. The fact that these patterns were so widespread suggests that a pattern will turn up though. Having analyzed over 288,848 words in nine languages, researchers are confident that these pre-noun pauses are something universal to human cognition, rather than weird tics of a specific culture’s customs or grammar.

Source: Why You Say 'Um' Before Certain Words by Mindy Weisberger, Live Science

On May 17th, 2018 we learned about

Narrowing down the reasons some people have a harder time with rules and requests

My son is currently in a difficult place, as he has decided to care deeply about being “the boss” while also being five years old. So as much as he’d like to dictate the terms of bedtime or timing of dinner, there are many moments when we can’t agree with the demands and judgments of a pre-schooler. There are signs that, as he grows older, he’s becoming a bit more understanding about when it’s appropriate to cede control to the adults around him, but there’s also a chance that he may be a naturally control-averse person. It’s a mindset that everyone’s encountered from time to time, as we all have moments where expressing defiance is somehow more important than solving the problem at hand, and yet we don’t really know much about how it manifests in our brains. Researchers are getting closer, but pinning down what makes some people have a harder time following “the rules” is proving to be a difficult task.

When being asked for something backfires

If you ask people to share their thoughts on freedom, rules and autonomy, you won’t actually get very far. Most of us, from age five to age fifty, generally feel like making our own choices is a pretty good idea, even if we don’t back those opinions up in our behavior. To come up with a more objective definition of control-averse behavior, researchers had volunteers play a money-trading game in an fMRI, observing brain activity while also looking for patterns in the way people conducted themselves when they weren’t explicitly thinking about if they were “the boss” or not.

Most participants were fairly generous with their partner when playing the game. Likewise, most participants didn’t like their generosity being questioned. During some rounds of “trading,” people’s partners would request a minimum amount of money to be handed over. Almost every participant balked at these requests, complying but handing over less money than if they hadn’t been asked. So for example, if a test subject would have normally shared $15, a request for $10 would spur the subject to share less, maybe only giving $10 or $11 that round. The more control-averse someone was, the more they were likely to reduce their generosity. When asked further questions about their motivations, people who were more control-averse also reported that they were more bothered by the implied lack of trust in their partner’s request as well as a general distrust if they didn’t understand why their partner would ask for a minimum amount. More than ideas about freedom, it seemed that the issue was in understanding the partner’s motivations.

A confusing basis in the brain

Since these behavior patterns were operating on a spectrum, with some people having more pronounced reactions to minimum requests than others, it still wasn’t enough to really define control-aversion. Fortunately, the data from the fMRI scans of participants’ brains helped find a more tangible clue, as control-averse people also showed pronounced activity in the inferior parietal lobule and dorsolateral prefrontal cortex. Those brain regions don’t explain everything at this point, as they linked to everything from math to moral decision-making, but they at least offer a more objective metric than asking for people’s opinions. As researchers look into these particular bits of anatomy further, there’s speculation that the activity seen in this study is the result of a person coming to terms with their own motivations and outside stimuli that they perceive as being in conflict with their goals, even if they’re just a minimum request.

It’s worth noting that as much as control-aversion sounds like a negative (and feels negative when its coming from a tired five-year-old), it’s not necessarily a bad trait to have. There are times when questioning authority or dogma can provide important leadership, helping the rule-breaker and everyone around them. However, in some contexts it obviously causes problems, leading people do to the clash with rules or laws for what seems like a very unnecessary reason.

Source: Why Some People Just Can't Have a Boss: Study Reveals Brain Differences by Bahar Gholipour, Live Science

On May 15th, 2018 we learned about

Researchers use RNA to move memories between snails’ brains

On a practical level, our brains require experience to learn and remember new information. As far as scientists can tell, that information is encoded in a network of synapses, or the connections between brain cells, in various combinations. This structural aspect of memory seems to require that brain cells construct synapses themselves, negating any chance of having new memories being imprinted or injected into the brain all at once. However, researchers are investigating other forms of information found in the brain, focusing on RNA molecules inside brain cells, instead of the connections between those cells. This has opened up some intriguing possibilities, including the ability to transfer memories from one brain to another.

Purposes beyond building proteins

RNA is a complex protein structure that plays a number of roles in cell functionality. It’s most commonly associated with transferring instructions from a cell’s DNA to actual protein production, but researchers are realizing that that is only one of its jobs in the body. To see if it can carry information about an individual animal’s experiences, researchers tried gently scaring some snails to see if RNA could hold information from a memory as well.

The experiment started with marine snails called California sea hares (Aplysia californica) which were given small electric shocks. As the research lead Prof David Glanzman, made a point to specify, the shocks weren’t strong enough to cause harm the snails, and were really only meant to get them to feel the need to retreat from a physical stimulus. After a bit of “training,” zapped snails would retreat from a gentle poke for as long as 40 seconds, while untrained snails would pull back only for a moment.

Injecting information

Once that experience-dependent behavior was established, researchers extracted RNA from brain cells of both groups of snails. The RNA was then injected into the brains of a third batch of snails who had yet to be poked one way or the other. Snails receiving “unzapped” RNA didn’t really change their behavior, reacting only briefly to gentle pokes from researchers. Snails who received RNA from a zapped snail had a bigger response, retreating from physical stimuli as if they had been trained to avoid shocks themselves. The difference in the RNA donors’ experience seemed to control how the recipient snail reacted as if they’d formed a memory on their own.

This seems like a big step towards injectable knowledge, but nobody is about to pick up a new skill in moments quite yet. Other neuroscientists point out that while this study suggests a role for RNA in memory, it doesn’t rule out the importance of synapses. Also, since snails only have 20,000 brain cells, there’s a good chance that the cognitive demand of retreating from a shock isn’t exactly on par with how our brains’ 100 billion brain cells handle new data. Still, it seems that some kind of information was shared via neurons’ RNA, demonstrating a need for further investigation.

My third-grader-asked: Did the first snail that got zapped then forget it got zapped when they took out its RNA?

This wasn’t mentioned, although memory removal would certainly be an interesting wrinkle in a world of injectable information. However, since researchers probably weren’t targeting a single brain cell in the snail’s brain, some memory of being zapped would be left behind in other copies of that RNA memory, assuming that’s how this was all working in the first place.

There also didn’t seem to be a problem with choosing which cells should recieve the RNA injection in the recipient snails, indicating that the “memory” didn’t need to be added to one cell in particular. That may be thanks to the relative simplicity of a snail brain, or that RNA memories are rather general in scope. Maybe they actually trigger physiological responses more than encode details of a specific moment in a snail’s life?

Source: 'Memory transplant' achieved in snails by Shivani Dave, BBC News

On May 6th, 2018 we learned about

Brain scans of crocodiles suggest that even our ancient ancestors could have appreciated listening to Bach

One of the most important parts of getting good data from an MRI is that the subject hold as still as possible, even when being asked to perform a task. This will ensure that the resulting images are clear and crisp, allowing researchers to get more precise data about how anatomy functions, from watching a dye circulate through a kidney to watching changes in oxygenation of specific brain structures in response to stimuli. It’s also a good idea for the subject to avoid biting the MRI technicians, particularly when the subject is a Nile crocodile.

Brains built to parse complex sounds and patterns

With a few extra precautions, such as light sedatives for the juvenile crocodiles (Crocodylus niloticus), researchers have managed to get the first scans of crocodile brains in action. They were presented with variety of stimuli intended to activate specific portions of their brains, such as visual processing centers in response to flashing green or red lights. Auditory responses were first tested with basic, synthetic tones at either 1,000 or 3,000 Hz. However, those sounds were then followed up with the more complex sounds of Johann Sebastian Bach’s Brandenburg Concerto No. 4, a composition used in many animal studies to see if the test subject differentiates between random beeps and a complex, structured series of sounds.

It would appear that the crocodiles did appreciate the music. While the beeps stimulated some auditory centers in the crocodiles’ brains, the concertos were processed by a wider set of brain structures, indicating that more cognition was taking place to unpack those sounds. The particular patterns weren’t completely novel, as they roughly followed the activity seen in birds or mammals when they listen to Bach. Of course, considering how distantly related crocodiles are to mammals, this is quite significant. Crocodiles last shared a common ancestor with birds around 240 million years ago, and mammals 320 million years ago. While it’s possible that this neurological pattern has evolved more than once, it’s probably more likely that it is something all these groups of animals inherited from a common ancestor as far back as the Carboniferous period, and is thus shared across all mammals, birds and reptiles.

Scanning brains in cold-blooded bodies

Of course, an appreciation of complex sounds and patterns may even be older than that, but we’d need to get more distantly related animals into an MRI to find out. Fortunately, this study has helped pave the way for future brain scans, particularly with the challenges of scanning cold-blooded animals like reptiles, amphibians and fish. MRI images don’t detect electrical activity between brain cells, instead showing where oxygen is being depleted in the brain. This is partially dependent on the animal’s body temperature, which is easier to deal with in mammals and birds since our warm-blooded bodies maintain a stable temperature on their own. The crocodiles required a lot of careful adjustments though, since even the MRI machine itself would raise the crocodiles’ temperature enough to change how they were using oxygen. With that experience under their belt researchers now hope to use these lessons with other creatures to discover which creatures’ brains can’t handle classical music.

My third grader asked: This didn’t hurt the crocodiles, did it?

The crocodiles didn’t experience pain, and apparently showed little signs of discomfort. While they were sedated, and their mouths and tails bound, the crocodiles seemed to be quite comfy when in the confines of the scanner tube. Once they were inside, they turned out to be very cooperative test subjects, holding still during the scanning process. In the end, they followed all the aforementioned guidelines, including the bit about not biting anyone.

Source: What Scientists Saw When They Put a Crocodile in an MRI Scanner and Played Classical Music by George Dvorsky, Gizmodo

On April 29th, 2018 we learned about

Sticks and string show how songbirds “see” ideas they share through sound

We’re still a long way off from being able to converse with a songbird like a Japanese tit (Parus minor), but after a lot of careful listening, we can at least tell when they’re tweeting about snakes. Like many birds, Japanese tits will shout out specific alarm calls when a threat is detected, helping to warn their kin in the area. This sort of punctuated vocalization has been found to be specific to the type of threat detected, allowing researchers to match specific sounds to specific concerns. Once the utility of these chirps was understood, it raised a new question- what does this chirp look like in the bird’s brain?

Ethologist Toshitaka Suzuki suspected that the tits processed a call about a snake in a similar way to humans. We know the chirp to warn about a snake is relatively specific, making it comparable to a single word in languages spoken by humans. When presented with a word like “snake,” most humans (but not all) will automatically visualize a rough approximation of the object being discussed. We might not necessarily picture a specific species of snake, but a serpentine form is likely to pop into our imagination. Suzuki’s hypothesis was that Japanese tits did the very same thing, although asking them to describe their thought process was still beyond his abilities as a bird translator.

Birds’ view of a snake-like stick

To work around the language barrier, Suzuki set up an experiment that let the birds demonstrate what was on their minds. A crude snake “puppet” was made from a stick, then hung vertically along a tree. Strings attached to the stick could make it wiggle back and forth, looking a bit like a slithering serpent if you were feeling generous. However, the lack of realism was key to the experiment- the goal was that the stick would only remind a bird of a snake if they were already picturing a snake in their heads.

The actual test came when birds could see the wiggling stick while listening to recordings of various Japanese tit calls. Non-specific alarm calls naturally caught the bird’s attention, but didn’t make them pay any special attention to the stick-puppet nearby. The alarm call for “snake,” however, did make the birds look twice at the vaguely snake-like object nearby, suggesting that the call for snakes made the birds immediately cue into visual stimuli related to snakes. To do this, the birds most likely had to associate the meaning of the alarm call with a visual representation of snakes, suggesting a very similar thought process to what is found in humans.

Patterns in perception

That last bit may not seem significant at first. If birds have chirps that operate as words, why shouldn’t they associate words with imagery too? Considering that bird brains don’t have the same functional structures as mammals, lacking the cerebral cortex we use for a lot of abstract thought, a better question may be why bird language operates like ours all. Why should they have evolved to solve these problems so similarly to humans? One explanation is that these patterns may be more widespread than we currently know. However, without clear bits of language to test against in other species, it may be hard to see if these underlying mechanics evolved long ago, or if humans and birds have simply converged on this solution to sharing, and picturing, our ideas.

Source: ‘Delightful’ Experiments Reveal What Birds See in Their Mind’s Eye by Brandon Keim, National Geographic

On March 8th, 2018 we learned about

Handwriting’s complicated connections to how well students perform in school

“Daddy, look, I can write my name!”

It was a triumphant moment for my third grader, not because she finally figured out how to spell her name, but because she’d learned to write it in cursive. It clearly meant a lot to her, and helped me rationalize why kids were still being taught to write in a way that they would probably be barred from doing in the future if they had teachers like I had in high school. With the additional need to learn to type in today’s world, worrying about handwriting seems a bit outdated, but there’s some evidence that it’s more useful than I’d imagined. Even hand-written printing may help kids develop both motor and academic skills, even in an era of buttons and touch screens.

How penmanship helps expose problems

Older studies have linked handwriting to kids’ academic success, although it wasn’t entirely clear if snappy penmanship actually promoted good grades, or just correlated with them. While kindergartners with better handwriting were found to have higher math and reading scores in second grade, it was possible that both skills were the result of some other factor that promoted academic success.

Other studies have since tried to pick apart how better fine motor skills might improve one’s math and writing ability. Researchers have started to find that handwritten words require more than just motor skills, as language comprehension can play a role in one’s use of a pen as well. For instance, children with developmental coordination disorder (“dyspraxia”) will write fewer words per minute than their peers, but there will be no sign of motor impairment in the way they wield a pencil. When it comes to writing words though, these children often pause in the middle of writing a word, leading to poorly formed, and spelled, words. This doesn’t show a definitive cause and effect, but it does reveal another aspect of how the motor control necessary to write can have an influence on the expression of language.

Screen time seems safe

While most schools still expect kids to become comfortable with a pencil, there is growing concern about that kids’ use of touch screens will stunt their handwriting skills, thereby hurting their academic skills in the process. More data needs to be collected on this topic, but preliminary studies are finding no cause for alarm. If anything, young kids who spent time poking, scrolling and swiping at screens actually achieved hit fine motor milestones earlier than expected. This isn’t to say that more screen-time will make for increasingly superior students, but poking at on-screen targets might be a way for children to practice their coordination before they’ve learned their ABCs.

Source: We can't say if touchscreens are impacting children's handwriting—in fact, it may be quite the opposite by Melissa Prunty & Emma Sumner, The Conversation

On March 1st, 2018 we learned about

Investigating how our brains determine when our bodies should have a drink

Your skin may seem dry, your mouth may be parched, but the experience of thirst is all in your brain. To be more precise, it’s in your ‘thirst center,’ a bundle of brain cells found in your hypothalamus. These neurons are tasked with the job of telling an animal when to get a drink, and just as importantly, when to stop sipping. Weirdly, that second command takes place well before the rest of the body can benefit from any new fluids, which has made untangling the exact functionality of this system a surprising tricky problem.

When the body wants water

The thirst center isn’t making us go for a drink at random. The hypothalamus takes in information about a lot of our physiology, including blood pressure, sodium concentration and more. When these systems are out of balance and more water is needed, one response is to create more of the hormone vasopressin in the pituitary gland, which then makes the kidneys try to reclaim water from any available urine. The second, but probably preferable response is to have the thirst center have us look for a drink.

As obvious as that response may seem, it’s taken years for researchers to isolate which cells were actually in charge of feeling thirsty. To identify exact which parts of the brain were tied to thirst, researchers turned to optogenetics, a technique that uses engineered neurons to be activated by light via implanted fiber optics. In this case, mice had their brain cells monitored and stimulated until they either became thirsty, or artificially had their thirst quenched without needing a drink.

In this process, it became clear that the amount of water an animal drinks is entirely up to the brain. Water won’t do a body much good until 10 to 15 minutes after it’s been ingested, whereas mice’s thirst center stopped them from drinking after only a minute each time. Somehow the brain felt it had had enough liquid, and that it was time to stop drinking.

Drinking disorders

This may sound pointlessly academic, but that’s only because it works so well for most of us. Whatever mechanism the thirst center may be using to measure our water intake, it’s generally helping us obtain a safe amount of water. If we ignore the thirst center, as some marathon runners have done, or the mechanism is damaged, as with people with psychogenic polydipsia, the results can be dangerous or even fatal. Cells swell and burst like balloons as they try to absorb the incoming water, a fate particularly damaging when it occurs in the brain. On the flip side, as people age they often have a weaker thirst response, and may forget to hydrate on a regular basis.

At this point, the investigation into how we feel thirst is actually moving out of the brain. Researchers are interested in muscle cells in the throat that help with swallowing, as there’s a chance that our sip-stopping thirst center may be gauging our water intake based on how quickly we swallow.

Source: Still Thirsty? It's Up To Your Brain, Not Your Body by Jon Hamilton, The Salt