Far Beyond Smell: How Your Nose Senses the “Texture” of the World (and the Future for Those Who Lost Their Sense of Smell)

When you inhale the aroma of freshly brewed coffee or pull back at the smell of smoke, it seems like it’s all the work of a single sense, right? In fact, what we call “smelling” is a sophisticated construction by our brain. It is an impressive teamwork between two different parts of our body.

This Anosmia (loss of smell) Awareness Month, we invite you to discover what happens behind the scenes of your nose. There is a second protagonist in this story — responsible for giving “texture” and physical sensation to smells — that not only protects us, but could be the technological key to restoring perception to those who can no longer smell aromas.

The Two Detectives of the Nose

Imagine that inside your nasal cavity, there are two detectives working together:

• The Olfactory Nerve: This is the identity expert. It’s the one that lets you know if a scent is vanilla, wet earth, or perfume.
• The Trigeminal Nerve: This is the “touch” expert. It doesn’t smell the odor, but it feels temperature, pain, and irritation.

You know that icy coolness when you smell a mint leaf? Or the burning sensation when smelling pepper? Or even the tingling in your nose when opening a soda? None of that is smell. It is the trigeminal nerve in action. Science calls this ability to “touch” smells chemesthesis. It is the union of these two detectives, along with taste, that creates the complete flavor of things.

How Does the Nose Know What is Hot or Cold?

If the trigeminal nerve doesn’t have a thermometer, how does it know that mint is “cold” and pepper is “hot”?

At the very tips of this nerve, there are microscopic sensors called TRP Channels. Think of them as super-smart locks that only open with specific keys:

• The TRPM8 sensor is activated by cold and menthol. It sends the brain that “open nose” sensation.
• The TRPV1 sensor is activated by heat and pepper.
• The TRPA1 sensor is our emergency alarm. It reacts to smoke, chlorine, or garlic, causing us to hold our breath or sneeze to protect ourselves.

These two detectives talk all the time. If the trigeminal nerve senses a very strong danger (like a harsh cleaning product), it releases chemicals that temporarily “turn off” the sense of smell. It is the body muffling smells to protect its most delicate cells.

The Smell GPS

Another fascinating detail: the olfactory nerve has no “GPS”. If you close your eyes, you can’t tell if a pure smell entered through your right or left nostril. The one that creates this spatial mapping of where the smell is coming from is exclusively the trigeminal nerve!

The Loss of Smell and the “Cyborg Nose”

And what happens when a person loses their sense of smell (anosmia)? The brain adapts. Interestingly, those who lose their sense of smell during their lifetime usually end up with a less sensitive trigeminal nerve. Conversely, those born without a sense of smell develop a super-powered trigeminal nerve to compensate for the lack of the other sense since infancy.

But the big news comes from technology. Since the trigeminal nerve usually keeps working even when olfaction fails, scientists have discovered that they can use it as an “alternative route” to send information to the brain.

In a recent study (published in 2025), researchers created an incredible device:

1. An “electronic nose” detects the scent in the air.
2. It transforms this scent into small electrical pulses (like vibrations).
3. A clip on the nose sends these pulses directly to the trigeminal nerve.

The result? After a training period, the brains of anosmic patients learned that “that specific vibration” meant “smoke,” and “another vibration” meant “mint.” The brain is so adaptable that it can learn a new sensory language. It is the first major step towards creating prosthetics that will restore chemical perception to people!

Anosmia Awareness Month: 5 Home Safety Tips

While these innovations make their way to the public, those living with anosmia need to adapt their routines, since the body has lost a large part of its natural danger alarm. If you or someone you love has anosmia, adopt these five simple practices:

• Rely on alarm technology: Your sense of smell won’t wake you up in case of smoke, but a sound alarm will. Install smoke and gas leak detectors around the house.
• Trust the label, not your eyes: You can’t tell if milk has gone sour just by looking at it. Make it a habit to write down the date you opened any package and strictly respect expiration dates. When in doubt, throw it out.
• Extra care when cleaning: Even if you don’t smell the strong scent of bleach, your trigeminal nerve still feels the chemical aggression and can silently become inflamed. Always clean with open windows and in a well-ventilated area.
• A safer kitchen: If possible, swap your gas stove for an electric or induction model (cooktop). This nips the risk of invisible leaks in the bud.
• Ask for a “sniff test”: Don’t be ashamed to ask someone you trust to take a quick sniff of those clothes stored away for months or a product before using it. It is a smart act of self-care.

The Grupo Boticário’s Smell Research Center remains passionate about understanding every detail of how we experience the world. Our commitment is to bring scientific knowledge that transforms not only science but everyone’s well-being.

References:

Karunanayaka PR, Lu J, Elyan R, Yang QX, Sathian K. Olfactory-trigeminal integration in the primary olfactory cortex. Hum Brain Mapp. 2024 Jul 15;45(10):e26772. doi: 10.1002/hbm.26772. PMID: 38962966; PMCID: PMC11222875.

Stanley HB, Lipp C, Mignot C, Weise S, Garefis K, Fieux M, Tsakiropoulou E, Genetzaki S, Dubreuil R, Ferdenzi C, Carulli M, Bertolini M, Rossoni M, Bertsch A, Brugger J, Hummel T, Konstantinidis I, Bensafi M. Substitution of human olfaction by the trigeminal system. Sci Adv. 2025 Nov 28;11(48):eadu7926. doi: 10.1126/sciadv.adu7926. Epub 2025 Nov 26. PMID: 41296861; PMCID: PMC12652247.