The Science of Aromatherapy: Ch. 1 Neurocircuitry of Smell

Posted on November 07, 2017 by Daniel Almeida | 55 comments

The Science of Aromatherapy

Welcome to the first of many posts in our mini blog course entitled “The Science of Aromatherapy: From Brain to Behaviour”. The goal of this series is to provide our readers with current scientific research investigating the effects of aromatherapy on the body and mind. Here you’ll find accurate information written by our resident neuroscientist and aromatherapist in training. The first few posts in this series will cover fundamentals of human anatomy and physiology so as to ensure that we all have a good understanding of how essential oils exert their effects. We’ll spend a majority of these introductory posts discussing the nervous system and stress hormones. Then we’ll explore a whole body of research that speaks to the benefits of aromatherapy. Whether it is insomnia, anxiety, depression, stress or even chronic pain, aromatherapy has been looked at. Interspersed amongst these posts will be our “Science to Practice” updates, where we’ll either feature a case study or provide you with tangible advice on how to effectively use aromatherapy for your own well-being.

Neurocircuitry of Smell

The sense of smell, or what is referred to in the scientific world as olfaction, is quite unique in its neurocircuitry. Odorant molecules start by binding to specialized olfactory receptors on olfactory receptor cells, of which there are millions. Interestingly, despite the various combinations of smells that our olfactory system can sense, humans only encode ~400 unique olfactory receptor types. You’re probably wondering, then, how this is possible. Well, smell is a combinatorial code of various olfactory receptor neurons being activated. So when you smell the brisk and energizing scent of peppermint essential oil, many different types of olfactory receptor neurons are firing to form a complex code that is sent through the olfactory nerve to the olfactory bulb. From the olfactory bulb information is routed to the piriform cortex, amygdala, hypothalamus, hippocampus and other limbic system structures through the olfactory tract. It’s due to the structural connections between the olfactory system and the brains limbic system that our perception of smell is intimately entangled with our experience of an emotion.

The Limbic System

 The Limbic System by Organic Aromas

As a neuroscientist with an expertise in psychiatric illnesses, I’d argue that the limbic system is one of the most beautiful circuits in the brain. It’s due to the psychological faculties regulated by these structures that it’s commonly referred to as the brains seat of emotion. Without getting too much into human neuroanatomy, let’s look at some of the major brain areas in this circuit.

The amygdala is our brains integrative center for emotions, emotional behavior, and motivation. Many behavioural neuroscientists that study the amygdala have focused on its role in fear and fear memory. Interestingly, studies suggest that odorants have the potential to trigger the recollection of strong emotional memories, the experience of which correlated with elevated activity in limbic brain structures, such as the amygdala. These odorants can lead to the recollection of both positive and negative experiences. It really depends on the memory that was encoded while the scent served as a contextual cue.

What is a Contextual Cue?

An example of contextual cues is as follows; have you ever had that experience where you have a thought to get something in another room but once you arrive in that new location you completely forgot what exactly that thing was? You then return back to the place where you had the initial thought and you now remember exactly what you needed? That’s a perfect example of context depending encoding and retrieval. Contextual encoding happens because of the spatial and memory consolidation properties of our hippocampus. In the case of emotional memories, the amygdala and hippocampus have a strong connection together. As such, the odorant serves as a contextual cue for the retrieval of the memory, the circuit is then activated and you re-experience an emotional state. Let’s do a bit of introspection, grab a notepad and write down 5 of your favourite aromas. Now write down a positive experience that you had that may have been paired with the smell and potentially explain why you like it. I’m sure that you’ve just discovered something that you never even knew about yourself.

Let’s look at one more important brain structure in this circuit, despite there being many more. The hypothalamus is involved in motivational behaviours and homeostasis (balance). It’s the part of our brain that regulates the hormones released from our pituitary gland. Motivational behaviours regulated by the hypothalamus include food intake, maternal behavioural, sexual behaviour, social behaviour, aggression and other simple behaviours. As for homeostasis, I think this is a great place to end our post and leave you in suspense as to the grand balancing act that the hypothalamus is well known for. I’ll give you a clue; it has a lot to do with our least favourite six letter word, STRESS.

 

Daniel Almeida

By Daniel Almeida, HBSc, PhD(c)

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25 Responses

Adam Fromson
Adam Fromson

December 11, 2017

After knowing the science behind Aromatherapy, don’t you think its time to get one for you?

Visit our website https://goo.gl/1T1it3 and get your’s right now..!!!

Gracina Cabanog
Gracina Cabanog

November 25, 2017

I have seen a wide variety of essentials oils here https://www.radhabeauty.com/collections/aromatherapy-massage

Gracina Cabanog
Gracina Cabanog

November 25, 2017

Very interesting read! Natural living has never been easier when you buy pure essential oils. Today’s world is busier and more stressful than ever. We’re connected to each other in many ways, but we seem to have lost the connection to ourselves. Adding essential oil blends to your daily life through aromatherapy and massage can renew the spirit and provide a deeper insight into our selves.

bambi l.
bambi l.

November 13, 2017

absolutely fascinating ! Essential oils can change your whole mind and body.

Veronica
Veronica

November 13, 2017

Informative article!

Cheryl
Cheryl

November 12, 2017

Good article, but it would be better in laymen’s terms.

Lindsey
Lindsey

November 12, 2017

Excellent article, Dr Almeida. I’m excited to read more!

Jeannette Smith
Jeannette Smith

November 11, 2017

This is very true; a certain scent brings back a childhood memory. I don’t recognize the scent and I am not able to reproduce or describe the scent. However, every blue moon when I come across the scent, I remember again.

Jen G
Jen G

November 11, 2017

oh. this looks awesome!!

Amanda Christensen
Amanda Christensen

November 11, 2017

Wow, very interesting!

Rachel
Rachel

November 11, 2017

I’m excited about this new series and learning new things or remembering what I already know but may have forgotten. Thank you! :)

Scotty
Scotty

November 11, 2017

Excellent read, looking forward to more in this new line of articles!

Betsy Barnes
Betsy Barnes

November 11, 2017

Very informative and useful article, thanks!

Natalie McLellan
Natalie McLellan

November 11, 2017

I would love to help my mum destress by getting her one of your diffusers ! Interesting article :)

Gord
Gord

November 11, 2017

This was a very interesting article to read.

Brookie B.
Brookie B.

November 10, 2017

Are there certain essential oils that are extra nurturing to the amygdala? Learning from you about the odorant encoding processes, I’m curious as to whether you can use an essential oil diffuser during distressing memory recall, (such as EMDR) or even during Cognitive Behavioral Therapy to re-encode a negative experience into a neutral or positive one. As someone with a history of panic attacks, (dumb) the thought of another token in my arsenal to recovery through scent is rather exciting. Fantastic information, Dr. Almeida!

Jennifer
Jennifer

November 10, 2017

Wonderful information!!

Karmela
Karmela

November 10, 2017

Very interesting read.

Judystolz
Judystolz

November 10, 2017

Thank you for all the amazing information.

Michele
Michele

November 10, 2017

Love this nebuliser. Essential oils are not watered down or destroyed by heat. Beautiful design that looks great in my home.

Xiomara M
Xiomara M

November 10, 2017

Interesting article! Everything you need to know to try aromatherapy.

Linda Lockwood
Linda Lockwood

November 10, 2017

For anyone struggling with health issues, give essential oils a try. Your going to find something positive in the experience!

GiGi W
GiGi W

November 10, 2017

I wish my olfactory system was stronger! But at night there is more humidity in the air and that is the only time I can really smell what is around me.This is helpful to hear that I might be able to remember where I left my keys if I use this diffuser!

Coressa B Clark
Coressa B Clark

November 10, 2017

Essential Oils has changed me forever!!! xoxo from Indiana

Mar_bo
Mar_bo

November 10, 2017

loved the part about contextual cues!

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