What happens in your head when you smell that scent that transports you to a holiday, to the arms of the love of your life, to a happy memory...?
To answer this question, we'll explain how your sense of smell works. You'll see, it's quite... surprising.
How does the sense of smell work?
When you smell something, it's becausean odorous molecule - which has escaped from a perfume, for example, or from a chocolate bar - has been captured by your nose. As it travels through your nostrils, the molecule makes a few checks to "olfactory lashes" - a bit like the ones you put mascara on (except that at the moment, when something shaped like a mascara brush arrives at this level of your nose, it's usually to do a Covid test).
These cilia contain olfactory receptors to which the odorant molecule is attached. A little subtlety: each cilium captures a different type of odorant molecule. Imagine: there is the "smell of freshly cut grass" cilium, the "smell of your lover's skin" cilium, the "smell of Nutella" cilium, etc...
Tastes and colours
Well, if it stopped there, it would be too simple. The funny thing is that we don't all have the same receptors. That's why we all have a more or less different sense of smell - and when we smell the same perfume, everyone will experience different smells and sensations!
Once captured by the receptors, the information is sent to the brain as a chemical message and is received as an "olfactory sensory image". A bit like a postcard, except that it is your olfactory neurons that send it. From the image, the brain analyses and determines the smell, with a message like: "roasted hazelnut + milk chocolate + sugar = hmmm no doubt, it's Nutella. Go and get a spoon".
Smells and emotions: a very strong link
Olfaction is a very special sense. In general, the information captured by our senses (sight, touch, etc.) is first processed in a small part of our brain called the thalamus: it sorts the information and determines preferences (like/dislike). Except that smells take a slightly different route... they go directly to two other areas of our brain: the amygdala and the hippocampus. These areas are dedicated to emotions and memories!
When you smell a scent, it is believed that your brain can associate one of six emotions with it: well-being, sensuality, disgust, comfort, vitality and nostalgia. These can be extremely powerful. For example, when you smell burnt, you feel disgust. This means that your brain has registered the fact that the smell may be dangerous to you and is telling you to get away (or rather, to take a cooking class before all the pots and pans are ruined). On the other hand, a smell can evoke a fond memory and make you feel confident. This is the case with sweet smells that often remind us of our childhood...
Emotions remain a real mystery and science still doesn't know everything about their links with smells. A lot of research is still going on, so we'll see you in a few years for the rest of the explanations!
And you, what smell makes you dream, smile, travel?
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Photo Credit: Unknown | Jules Théret
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