Why Do You Stop Noticing Scents After a While?

The y is actually simple. Experts in biology, psychology, and volatile aroma compound physics a k a. The science of smells all pretty much agree that you stop noticing a smell after a short while because your brain wants to concentrate on scanning for new and potentially hazardous smells. That's because sharp gross sense may indicate the dangerous predators in the area, or that there's a diseased work, or that the thing that you're about to eat should, under no

circumstances be eaten. But if you stick around a particular scent, your brain figures it's already done warned you about that one, and thus freese up its processing power for logging new sense and changes in scent intensity. This is called olfactory adaptation. How your brain accomplishes this type of sensory adaptation is more complicated. When you notice a smell, a molecule of volatile aroma compound, that is, a gaseous smelly thing has

entered your nose. Our nasal passages are lined with somewhere around ten million neurons. You can think of each of those neurons as a tiny tree designed to pick up on a single type of scent. They have branches called dendrites, each covered in smaller structures that are called cilia and are kind of like leaves. Going with the tree concept, the cilia are studied with odor receptors. A molecule of whatever kind of scent that neuron tree specializes in sensing

combined to each odor receptor. When that binding happens, it sets off an electrochemical chain reaction. In the end, the neurons sends an electrical impulse through its action. Metaphorically, it's route up to the olfactory bulb in your brain. That's the part of your brain that processes scent stimuli and sends the information on to other parts of your brain.

Very basically, the more molecules that bind to a given type of scent receptor throughout your nasal passages, the stronger the signal to your brain will be and the stronger you will perceive the scent to be. But we can adapt to a sense presence within a few breaths. Researchers think that there are a couple of things going on here. First, in those tree like neurons in your nose, at least one bodily chemical calcium ions to be specific, plays double duty.

It both helps send electrical impulses to the brain and helps stop those electrical impulses. After a few molecules have bound themselves to the scent receptors on these cilia leaves of a given neuron, chemicals from that electrochemical chain reaction start building up in the neuron. Although they usually make impulses happen, their build up will prevent the neuron from

sending further impulses to the brain for a while. The second thing going on here is that there's some kind of feedback loop among your nasal neurons and your olfactory bulb. Researchers aren't precisely sure how it works, but we know what happens because they've conducted experiments where they've exposed only one nostril to assent neurons in the other nostril will start adapting to it. But there are more questions here. How do different sense and different lengths of exposure lead

to different adaptations? Why can you never smell your own home the way that other people experience it. The answer science has to give us right now is basically shenanigans, because the perception of scent isn't just physical, it's psychological. What other parts of your brain do with the scent information that the olfactory bulb sends them absolutely factors in and in ways that researchers are still trying to suss out. Today's episode was written by me Weird and produced by

Tyler Clang. I'm supposed to remind you to contain yourself in brain stuff themed t shirts from our online shop at t public dot com slash brain stuff, and of course, for lots more on this and other topics that won't fade into the background, visit our home planet, how stuff Works dot com