Posts Tagged ‘tongue’

by David Nield

How exactly do our brains sort between the five taste groups: sweet, sour, salty, bitter and umami? We’ve now got a much better idea, thanks to research that has pinned down where in the brain this taste processing happens.

Step forward: the insular cortex. Already thought to be responsible for everything from motor control to social empathy, we can now add flavour identification to its list of jobs.

It’s an area of the brain scientists have previously suspected could be responsible for sorting tastes, and which has been linked to taste in rodents, but this new study is much more precise in figuring out the role it plays in decoding what our tongues are telling us.

“We have known that tastes activate the human brain for some time, but not where primary taste types such as sweet, sour, salty, and bitter are distinguished,” says one of the team, Adam Anderson from Cornell University in New York.

“By using some new techniques that analyse fine-grained activity patterns, we found a specific portion of the insular cortex – an older cortex in the brain hidden behind the neocortex – represents distinct tastes.”

Anderson and his team used detailed fMRI scans of 20 adults as well as a new statistical model to dig deeper than previous studies into the link between the insular cortex and taste. This helped separate the taste response from other related responses – like the disgust we might feel when eating something sour or bitter.

Part of the problem in pinning down the taste-testing parts of the brain is that multiple regions of neurons get busy whenever we’re eating something. However, this study helps to cut through some of that noise.

In particular, it seems that different tastes don’t necessarily affect different parts of the insular cortex, but rather prompt different patterns of activity. Those patterns help the brain determine what it’s tasting.

For example, one particular section of the insular cortex was found to light up – in terms of neural activity – whenever something sweet was tasted. It’s a literal sweet spot, in other words, but it also showed that different brains have different wiring.

“While we identified a potential sweet spot, its precise location differed across people and this same spot responded to other tastes, but with distinct patterns of activity,” says Anderson.

“To know what people are tasting, we have to take into account not only where in the insula is stimulated, but also how.”

The work follows on from previous research showing just how big a role the brain plays in perceiving taste. It used to be thought that receptors on the tongue did most of the taste testing, but now it seems the brain is largely in charge of the process.

That prior study showed how switching certain brain cells on and off in mice was enough to prevent them from distinguishing between sweet and bitter. The conclusion is that while the tongue does identify certain chemicals, it’s the brain that interprets them.

The new research adds even more insight into what’s going on in the brain in humans when we need to work out what we’re tasting – and shows just how important a job the insular cortex is doing.

“The insular cortex represents experiences from inside our bodies,” says Anderson. “So taste is a bit like perceiving our own bodies, which is very different from other external senses such as sight, touch, hearing or smell.”

The research has been published in Nature Communications.

https://www.sciencealert.com/now-we-know-the-part-of-the-brain-that-tells-us-what-we-re-tasting

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by Lambeth Hochwald

It’s been hammered into our heads to brush twice a day, floss once (though that’s up for debate) and maybe rinse with a fluoride mouthwash. But recently, another chore has been suggested as an addition to our dental routine: tongue scraping. But is this ayurvedic practice that dates back to ancient India really worth your while?

We went to two experts to find out if you should start your day scraping your tongue.

Dental hygienist Sam Williamson, owner of Teeth Whitening Belfast in Ireland, recommends the practice to all of his patients.

“Most of my clients don’t realize the effectiveness of tongue scraping until they actually do it and see all the gunk that comes off their tongue,” he says. “The tongue is the perfect breeding ground for bacteria, but although we take care of our teeth and our gums regularly, we don’t pay nearly as much attention to our tongue.”

The bacteria on your tongue is one of the main causes of bad breath, so scraping it regularly can significantly improve your breath over time. In fact, a recent study showed about 85 percent of all bad breath cases begin in the mouth and half are caused by bacteria residue on the tongue. Brushing your tongue is “the best way to ensure that your breath stays fresh throughout the day,” Williamson says.

Kimberly Harms, DDS, a dentist in Farmington, Minnesota, and a spokesperson for the American Dental Association, says “your taste buds in the back are made for bacteria to hide.” And when your mouth has a lot of bacteria in it, you can taste it. “That sour taste is often due to bacteria,” she says.

If you often suffer from dry mouth, this quick health routine can help that, too. “If you’re not producing enough saliva when you chew, you my have digestive issues,” Williamson says. “Scraping can help.”

How to do it

“A scraper is an efficient way to remove all that’s coating your tongue,” Harms says. Here are four things to keep in mind as you scrape:

1. Buy a dedicated tongue scraper (they cost as little as $6) that comes in plastic or metal and is usually shaped like the letter U.

2. Always be gentle — scraping your tongue should never hurt.

3. Scrape only five to 10 times, Harms suggests.

4. Don’t go too deep. “Since we have a gag reflex, be sure not to put the scraper too far back in your mouth,” she adds.

“It’s a wonderful thing,” Harms says. “We don’t like to praise things without research but tongue scraping makes sense. If you’re successful at brushing twice a day and flossing daily, great. Do that first. Consider tongue scraping a great adjunct to good oral hygiene.”

http://www.mnn.com/health/fitness-well-being/stories/what-you-need-know-about-tongue-scraping