Smells, moods and memories

Scents and smells are such an integrated part of our daily lives we tend to ignore it – until it warns us! Scents warn us if food is safe to eat, if there is a fire close by or even if a specific person is close by. We have distinct favourite smells and fragrances and some less-favourite. But what is a scent and why is it connected to memories?

What does a smell look like?

Smells are chemical molecules that travel through air or water and they are light enough to be moved around. These chemical molecules are everywhere but only when they are captured in our noses and trigger our olfactory neurons at the back of our noses do we realise they are there.

Because the molecules have to travel through air to reach your nose it needs to be in gas/vapor form. Some molecules are easier to vaporise and those are called volatile scents. Other scents require more energy in the form of heat.

Take a bunch of flowers for example – you can smell them when you enter the room, their scent molecules vaporised at room temperature, whereas several of the spices in your cabinet only really have a scent once you add them to food and heat them up.

In scent mixing the volatility index is what distinguish different scents in top, middle or base notes. Depending on the use and the rate of vaporisation, the fragrance will develop and change over time as they heat up.

Why are smells the best memory recall?

When a smell molecule reaches the back of your nose where the olfactory neurons are located it creates an electrical impulse. These impulses travel to the thalamus, a central system of the brain that interprets and analyse all the sensory information.

The thalamus transmits the smell information on to other sections of the brain, including the hippocampus and the amygdala. These are the key regions of the brain that are involved in memory and learning.

Because the amygdala and hippocampus are the emotional centers and smell triggers memory retrieval and storing for those regions, your memory is more emotional based. You might not remember all the finer details of a person or a place but you will immediate remember how they made you feel.

Choosing your fragrances

Because scents and smells bring back emotional memories and also create them, the fragrances you select for your soap recipe will always bring back a memory of how you felt while making it. The joy of accomplishing something amazing, the smell of elation and wonder and the scent of sharing.

Experiment with different fragrances, build a library of emotions and pour your heart in your soap. No-one will be able to replicate it and it will be uniquely you in every memory.

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