Friday, November 20, 2015

Taste - it's all in your head

When we taste a food, whether it be sweet, salty, bitter, sour, or umami (savory), we think that our tongue is responsible for telling the brain what it is. Instead, researchers found that the brain is responsible for interpreting what the taste is based on which group of neurons the chemical signal is sent to. To put it more simply, if you eat a sweet food and the sweet neurons are suppressed, the sweet taste receptors in the tongue will still be activated, but the food will not taste "sweet" anymore. On the other hand, if the sweet receptors are activated and the others are suppressed, all foods will "taste" sweet.

To test this, researchers gave mice a drug to suppress either the sweet or bitter neurons. Then they gave the mice sweet and bitter foods. The mice that had the bitter neurons suppressed could only taste the sweet foods and vice versa. They also tested these neuron groups by activating the sweet or bitter neurons while the mice were drinking water. When the sweet neurons were activated during drinking, they "observed behavioral responses in the mice associated with sweet, such as impressively increased licking". When the mice were drinking water with the bitter neurons were activated, the mice started gagging and performing "taste-rejection" behaviors. On the bright side, once the drugs were flushed out of the mice's system, all of their "tastes" returned back to normal.

Imagine if we could make all the healthy foods "taste good" and unhealthy foods taste bitter, especially to those who want to change their eating habits. More often than not, I don't eat healthy foods because some of them activate my gag reflex for some reason (other times it's the cost factor that keeps me away, but that's a different story). If I could take a pill before I eat to make that problem go away, I might be more inclined to eat those foods. Also, if I know I have a problem with over-eating sweets, I could take a pill to activate my bitter neurons to deter me from eating too much sugar. This was an interesting study to learn about and I'm curious to see where they take it from here.

References:

Scientists turn tastes on and off by activating and silencing clusters of brain cells

Yueqing Peng, Sarah Gillis-Smith, Hao Jin, Dimitri Tränkner, Nicholas J. P. Ryba, Charles S. Zuker. Sweet and bitter taste in the brain of awake behaving animals. Nature, 2015; DOI: 10.1038/nature15763

7 comments:

  1. How did they detect whether the mice were tasting bitter or not? Based on neurological activity? I am curious how can you tell what an animal is tasting. Humans-they should have tried it on, but I guess that is illegal.

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    1. They just based it on the behavioral responses, such as gagging, since that is a response that is hard-wired to be activated, not learned, since bitter foods/tastes are usually associated with "potentially noxious chemicals".

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  2. I have to admit, I spent a few moments laughing to myself picturing the confused mice making faces when they went to drink from their little water bottles... But if they are able to pin down the specifics of this a bit more, I look forward to the days of pizza flavored water and sushi flavored broccoli and all that jazz. We have managed to corrupt flavor and sensory perception pretty thoroughly just by manipulation of ingredient ratios, so this will be interesting to see the neurological impact of.

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  3. I have to admit, I spent a few moments laughing to myself picturing the confused mice making faces when they went to drink from their little water bottles... But if they are able to pin down the specifics of this a bit more, I look forward to the days of pizza flavored water and sushi flavored broccoli and all that jazz. We have managed to corrupt flavor and sensory perception pretty thoroughly just by manipulation of ingredient ratios, so this will be interesting to see the neurological impact of.

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  4. This would be great for my Dad since he has diabetes and cannot stay away from sweets at all! If this could make all those sweets taste bitter then I'm sure he won't eat them anymore and better his health.

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  5. I personally do not like vegetables (or anything healthy) so this would be great for me! This would also be great for those who had to take "nasty" medicine on a daily basis!

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  6. In a way it isn't a surprise that taste perception is largely controlled by the brain (cause, like ALL perception is), but it's kind of cool that they can target these neurons. I wonder if something weird hasn't happened to my neurons. A few years ago, I had some still to be identified parasitosis in my gut. TMI, maybe. Anyway, I was on a clear liquid diet for 10 days, like three times in two months. The only meaningful source of calories came from drinks sweetened with sucrose. After about one week, I couldn't drink those anymore, because the sweetness would make me gag. Strangely, even though I'm so over my parasite, sweetness often makes me gag.

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