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The Science Behind Smell

By March 29, 2022 April 6th, 2022 No Comments

As one of our primary senses, smell has a powerful impact on how we perceive what is around us. For centuries, scientists have been perplexed about how exactly the olfactory sense works, and what triggers it. How can our brain detect the different scents carried by the perfumes around us? In this article, we will be discussing the mechanism behind the sense of smell, how crucial it is to our perception of our surroundings, and how it is intrinsically linked to our memories.

What is Olfaction and How does it Work?

Olfaction is the technical term for the sense of smell that we possess. Our ability to perceive odor is possible due to the olfactory nerve. This nerve consists of several olfactory receptor cells that line the mucous membrane in your nose.

The molecules that trigger the olfactory sense are airborne and attach themselves to these cells. What makes olfaction unique compared to other senses is that these receptor cells themselves are neurons. This means that they’re directly connected to our brain through the olfactory nerve. This way, the olfactory nerve is on the one hand linked to our brain while on the other, to our surroundings.

Whenever an odorant molecule attaches itself to the olfactory receptor cells, an electrical impulse called synapse is produced. Within three synapses, which is essentially just a tenth of a second, our brain can identify the odor. In this manner, the brain can detect up to a trillion smells. There are about 400-1000 receptor cell types in our nose and they keep regenerating throughout our lifetime.

Smell and Memory

Have you sniffed a perfume and immediately remembered a memory or a person associated with it?? How does our brain connect what we smell to our memories?

The synapses produced by the receptor cells cause signals that are detected and refined by the olfactory bulb in the brain. For further processing, these refined patterns are sent to the piriform cortex. Here’s the best part.

The olfactory bulb is connected to the area in our brain that regulates our emotions. When our brain detects a certain odor, it is instantly able to associate it with a certain emotion that we have experienced before, due to this connection. This way, even before fully recognizing the source of the smell, we associate it with a particular memory or primordial experiences. We can differentiate food from other things due to this. In fact, we can exactly pinpoint what we are smelling before we see it. This is also how we can recognize perfumes that people wear and differentiate one scent from the other.

The Oldest and the Fastest

The olfactory sense is the primordial sense; it’s something even bacteria possess to identify the chemicals in the air and water. Most creatures evolve to identify smell even before they can see, hear, or touch things. Unlike other senses, the synapses transmitted by the olfactory receptors are directly relayed to the olfactory bulb and processed. Because of this, the brain can sense smells faster than say, something that we’d see or hear. Thus, it is safe to say that our olfactory sense is the oldest and fastest sense we possess.


The olfactory sense is crucial to help us identify our surroundings and perceive them with due consideration of our experiences and memory. If nothing else, we would have missed out on the amazing perfumes around us that are carefully created to delight us.


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