You smell with your tongue? Yup, there’s more than a lick of ...


You smell with your tongue? Yup, there’s more than a lick of truth to it

Researchers say the groundbreaking findings could provide a solution to obesity

Sarah Knapton

Humans can smell with their tongue as well as their nose, scientists have discovered.
Dr Mehmet Ozdener, a cell biologist at the Monell Chemical Sense Centre in Philadelphia, tested human taste cells after his 12-year-old son pointed out that snakes would extend their tongues to smell the air around them.
Although snakes use their tongue to direct smell molecules to a special organ in the roof of their mouth, rather than sensing them directly, Dr Ozdener found that humans carry odour receptors in taste cells on the tongue.
The findings suggest the two senses of smell and taste first meet in the mouth rather than the brain as previously thought.
And it may explain why flavours that cause the greatest sensations, such as chilli and menthol, cause similar tinglings in the mouth and nose.
Previous research has shown that much of the “flavour” of food and drink comes from the smell, and people with a blocked nose usually report a lack of taste when they eat.
The team says the finding may help them create sprays that made unhealthy food taste bad, to avoid people becoming obese.
“Our research may help explain how odour molecules modulate taste perception,” said Dr Ozdener.
“The presence of olfactory receptors and taste receptors in the same cell will provide us with exciting opportunities to study interactions between odour and taste stimuli on the tongue.
“This may lead to the development of odour-based taste modifiers that can help combat the excess salt, sugar and fat intake associated with diet-related diseases such as obesity and diabetes.”
For the research, the team used a method known as calcium imaging to show that human taste cells respond to smell molecules in a manner similar to receptor cells in the nose. When taste cells are triggered by molecules calcium ions produce signals which can be detected.  A second experiment demonstrated that a single taste cell could contain both taste and smell receptors at the same time.Commenting on the findings, Charles Spence, professor of experimental psychiatry at Oxford University, said: “The results are definitely very intriguing and new.
“There might be a link to the back-of-throat sensations one gets with an extra virgin olive oil, or quality aged parmesan cheese. There is a kind of burn or tingle that doesn’t seem to be a straightforward taste or smell.
“There is a close interaction between taste sensitivity, nasal responsiveness and the common response to chilli or wasabi, or menthol, where the same compound stimulates multiple receptors – giving rise to bitter taste, minty smell and cooling sensation.“As a psychologist, I want to know if there are any perceptible consequences should multisensory integration occur in taste cell, if that is still the right name.”The research was published in the journal Chemical Senses.
– Telegraph Media Group Limited (2019)

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