August 22, 2023
Author: JC Sushma Swaraj
Editor: Manish Verma
Have you ever observed how your mood lifts to the aroma of the morning coffee and to the freshness of blooming flowers or how the smell of some food triggers your hunger… if we carefully observe at our lives, certain experiences make us question and feel fascinated by the deep connection our sense of smell has to our brain. To understand this networking let’s dig into the neuroscience of smell and how it impacts our mental and physical well-being.
The Neuroscience behind the Aromatherapy
Aromatherapy is an ancient practice involving the application of essential oils to enhance the brain functioning that is now being supported by modern research. The neuroscience of aromatherapy explores the intricate connection between scent, the brain, and its profound impact on our cognitive and emotional well-being.
The Synaptic Organization of the Brain
When we encounter an aroma, it sets off a complex series of events that reveal the intimate connection between our olfactory system and the neural pathways of the brain.
1. The Olfactory Pathway
Humans possess a keen sense of smell, which is essential for distinguishing vital odors required for good health. This includes being able to smell smoke to detect fires and recognizing the bad smell of spoiled food to avoid eating it.
Aromatherapy’s ability to elicit strong emotional responses is rooted in this connection.
Upon inhaling an aroma, scent molecules or odorant molecules travel through the nasal passages and bind to the receptors present on olfactory sensory neurons called Odorant Receptors (ORs). The olfactory receptors can recognize a myriad of different odor molecules depending on their protein sequence. Each olfactory neuron expresses one special kind of odorant receptor which upon binding to these molecules convert chemical signals into neuronal impulses. (See Fig below) For this discovery, Linda Buck and Richard Axel were conferred with the Nobel Prize in Medicine in 2004.
These neuronal impulses are subsequently sent by the receptors to the olfactory bulb, a neural structure positioned in the front of the brain that serves as a gateway for scent information. These impulses are then sent to the limbic system, a primitive region of the brain responsible for emotions, memory, and behavior.
The limbic system’s proximity to the amygdala, hippocampus and orbitofrontal cortex (OFC) are linked to emotional processing and memory, means that scents can trigger powerful recollections and sentiments. This explains why a particular aroma can evoke vivid memories or induce a surge of emotions, sometimes even when words fail to do so.
2. The Hypothalamic Connection:
Furthermore, the olfactory system is closely intertwined with the hypothalamus, a brain region responsible for regulating various physiological functions such as sleep, appetite, and stress responses.
That’s how Certain scents, like lavender or chamomile, have been linked to promoting better sleep quality and reducing stress levels, possibly by modulating the hypothalamic activity.
3. The Chemical Pathway:
Beyond the limbic system, aromatherapy can also influence neurotransmitter activity. Some essential oils have been found to impact the release of neurotransmitters like serotonin and dopamine, which play crucial roles in mood regulation and pleasure.
For example, the aroma of lavender has been shown to have a calming effect, possibly due to its interaction with GABA receptors, which promote relaxation.
Benefits Of Aromatherapy:
Digging deep into the neural involvement in aromatherapy, research sheds light on the potential therapeutic applications of scents. Till now, Aromatherapy has been explored as a complementary approach to managing various functions and conditions including:
- Mental Wellness
Essential oils such as lavender, chamomile and bergamot are proved to be effective in stress reduction and improved sleep quality providing a sense of relaxation by reducing heart rate and calming nervous system.
- Mood enhancers:
While the sweet floral scents of rose and Jasmine evoke feelings of happiness and positivity acting as aphrodisiacs and creating romantic ambience. Citrus oil, lemon and orange oils boost energy and revitalize the body.
- Pain relief:
Commonly used balms contain eucalyptus oil or peppermint oil for their cooling and analgesic property.
- Allergy aid:
Anti-inflammatory properties of eucalyptus and tea tree oil help in congestion, allergies and wound healing aiding in acne, athletes’ foot and insect bites.
- Cognitive effect:
Lavender essential oil along with rose has proved to improve learning and memory by 226% in the regimen of 6 months in elderly.
Top Essential Oils for Aromatherapy
- Lavender Essential oil
Derived from the flowers of the lavender plant through distillation have a positive impact on Nervous system and can be used for:
- Skin Conditions Like Acne, Eczema, Sun Burn, Wound Healing,
- Mental Wellbeing- Anxiety, Depression, Insomnia
- Miscellaneous- Menstrual Cramps, Bug Repellant.
- Peppermint essential oil
Its main components- Menthol and Menthone offers wide variety of applications including:
- Medical conditions like irritable bowel syndrome (IBS), certain digestive problems, Nausea, Common cold, itching, muscle pain and headache.
- Pleasant taste and odor make it compatible to use in various pharmaceutical preparations of Mouth washes. Soaps and Cosmetic products.
- Eucalyptus essential oil
It is nothing new to us, the popular vapor rub has almost 1.2% eucalyptus oil. But that’s not all. Apart from respiratory relief it also acts as insect repellant, disinfectant for wounds, control sugars in diabetes, speedup wound healing, eases joint pain.
- Teatree oil-
It is gaining lot of popularity in skin and hair care due to inexpensiveness and natural alternative to chemical based treatments for fighting acne, dandruff, Psoriasis and Athlete foot.
Apart from that, other properties such as antiseptic (wide range of microbes including fungus, virus and bacteria), wound healing, hand disinfection, bug repellant, natural deodorant makes it high in demand.
- Jasmine essential oil
Jasmine is the most found flower plant. Apart from its beautiful white flowers, the commonly used scent in perfumes causes increase in behavioral arousal and found to be effective in
- Depression
- Aphrodisiac
- Antiseptic
- Antispasmodic
- Insomnia
- Anti-inflammatory- Diabetic Ulcers, Psoriasis,
- Menopause symptoms like Hot flashes and depression
- Promote lactation
Using essential oils for night aromatherapy:
Add few drops of essential oil to
- Diffuser and run it in the room
- Inhale directly from the bottle
- Create aromatic steam by adding to Bowl of hot water
- Dilute in a carrier oil, add to Bath and soak for 2 hours before bed
- Rub on your wrist, temple and neck by mixing with carrier oil.
Carrier oils are oils without strong odor that can be used as base oil to dilute essential oils and includes fractionated coconut oil, almond oil, jojoba oil, olive oil, apricot oil and many more.
Safety precautions:
Just cause essential oils are natural it doesn’t mean they need no precautions.
Consider the following before using aromatherapy.
- Follow dilution ratio using dilution and usage guidelines
- Steam distilled cinnamon, clove and lemongrass leaf can irritate skin and mucous membrane. Conduct a patch test and consider dilution ratio, and recommended dosage and duration guideline.
- Diffuse in well- ventilated area for 30-minute interval and take regular breaks.
- Ensure pets have choice to leave the room in case the aroma doesn’t suit them.
- Watch for allergic reaction.
Conclusion:
The neuroscience of aromatherapy reveals a captivating symphony between scent and the brain. With ongoing research, we can deepen our understanding of how aromas can shape our emotions, memories, and overall mental state. The power of aromatherapy lies not only in its sensory allure but in its ability to harness the intricate neural pathways of the brain, offering a unique and holistic approach to promoting emotional and cognitive health. Since few case studies have raised issues regarding its safety, more studies are needed to evaluate the dosage, safety and efficacy of the essential oils in aromatherapy.
References:
- Vilela, A., Bacelar, E., Pinto, T., Anjos, R., Correia, E., Gonçalves, B., & Cosme, F. (2019). Beverage and Food Fragrance Biotechnology, Novel Applications, Sensory and Sensor Techniques: An Overview. Foods (Basel, Switzerland), 8(12), 643. https://doi.org/10.3390/foods8120643.
- Koulivand, P. H., Khaleghi Ghadiri, M., & Gorji, A. (2013). Lavender and the nervous system. Evidence-based complementary and alternative medicine : eCAM, 2013, 681304. https://doi.org/10.1155/2013/681304
- Lakhan, S. E., Sheafer, H., & Tepper, D. (2016). The Effectiveness of Aromatherapy in Reducing Pain: A Systematic Review and Meta-Analysis. Pain research and treatment, 2016, 8158693. https://doi.org/10.1155/2016/8158693
- Moss, M., Hewitt, S., Moss, L., & Wesnes, K. (2008). Modulation of cognitive performance and mood by aromas of peppermint and ylang-ylang. The International journal of neuroscience, 118(1), 59–77. https://doi.org/10.1080/00207450601042094