Nisha Ekanathan

Project

InCANDLEscence Webpage

Presentation

Progress Log

Capstone Essay

Nisha Ekanathan

Caballero

English 4

5 May 2020

Olfaction in the Human Brain

The human brain has the ability to identify and distinguish over one trillion scents. Scientists previously concluded that the average human could name around 10,000 scents, but now studies suggest that the number has increased (Marin). The power of our nose is much more significant than one fact can explain, and it lays the foundation for the entire system of our brain. To further explore this, my capstone will consist of a study to examine the way in which we use our sense of smell and the impact it has in our daily lives. I will create candles that resemble a variety of fragrances, and I will survey groups of people to gather information about their feelings towards each candle’s scent. As support to this project, I have researched the olfactory system and the actions that occur to recognize scents, as well as the influence it has on other functions in our brain. Essentially, olfaction is another term for our sense of smell. Understanding the role of olfaction in our bodies can allow us to maintain a strong and healthy brain that is fit for our lifestyle. Olfaction is a powerful and important sense that influences thoughts and emotions through its functions in our brain.

The olfactory system consists of many parts of the brain that work together to process odors. To begin this process, olfactory receptors located in the olfactory epithelium detect air molecules from fragrances. Once detected, the cells then send nerve signals to the olfactory bulbs which work together with the piriform cortex to identify a scent. When identifying a scent through a sniff, most of this occurs through the orthonasal pathway, which connects from our nose to the back of the nasal cavity. However, the nose is not the only device that allows us to effectively smell odors. It is possible to also recognize odors through the flavors in food we consume. The retronasal pathway helps us do so because it is a channel that connects the throat to olfactory receptors in the nasal cavity (Bailey). The scents detected in flavors along with information from the sense of taste can make each bite of food more enjoyable. Near the center of the brain is the thalamus, which also receives some smell information from the olfactory bulbs and assists in this process (Marin). Many individual sections in our brain have specific responsibilities that allow the olfactory system, activated through our nose and throat, to function properly.

Because of its convenient location, the thalamus is not only beneficial for taste but is also involved in the connection of scents and memories. Smells have a significant influence on our mood and can trigger past memories due to the links and connections of the olfactory system in our brain. The thalamus, which helps with taste recognition, sometimes sends the signals received from the olfactory bulbs to the hippocampus and amygdala, which are involved with learning and memory (Marin). Stimulating this area of the brain can also be done by simply breathing through our nose. Studies show that sniffing a fragrance through our nose strengthens and improves our memory, thus activating thoughts about experiences that correlate to that specific scent (Berbari). Even when we are not actively breathing through our nose, the hippocampus and amygdala can still be stimulated through the limbic system. The olfactory system is linked to the limbic system which not only uses the hippocampus and amygdala to process memories (Bailey), but it also works with emotions. The limbic system has the ability to activate before the cortex, which can sometimes cause emotional responses to scents even before we can recognize them (“Smell”). The limbic system and the thalamus, involved in the process of olfaction, also have effects on our mood and behavior.

In addition to the limbic system working with emotions related to fragrances, its capabilities also help form our opinions. Each individual human has unique opinions on what is considered a pleasant versus an unpleasant scent, but sometimes these opinions can be influenced by other factors. The limbic system can cause emotions to dictate whether or not fragrances are pleasant. Usually, positive emotions cause the brain to find the scent more admirable than a scent that is associated with negative emotions (“Smell”). However, it is not always the case that our mood and behavior have an impact on our feelings toward a scent. The piriform cortex, that collaborates with the olfactory bulbs, uses its knowledge from noticing other people’s reactions in the past towards specific scents to develop its own ideas (Bailey). Past experiences associated with particular fragrances along with personal preferences of an individual can also play a role in one’s opinion about a fragrance (“Smell”). Feelings about scents can be shaped by a person’s emotions, experiences, personal preferences, as well as the responses of other people.

Being linked to many other aspects of our brain and body, olfaction is a strong and significant sense that cannot be undervalued. The sense of smell has the ability to multitask and is beneficial in many ways towards our mind and body. Tiny cells in the nostrils known as cilia filter the air we breathe through our nose. It stabilizes the air’s temperature to prevent extreme heat or cold from entering our body. Advantages of breathing through our nose also include stimulation of the brain, a calmer mind, and controlled heart rate and blood pressure (Berbari). The olfactory system is very beneficial, but only because it is an extremely significant part of the brain. More than half of the brain is stimulated only during olfaction, because it also involves other senses besides itself. One sniff can activate the brain, olfactory receptors, emotions, and memories (Marin). Olfaction is an important sense in humans due to its ability to smell and activate the majority of the nervous system while overall benefiting the brain and body.

Scents that trigger the nervous system come in forms that can be very powerful, such as essential oils, which have a significant impact on the brain’s functions (Heid). Aromatherapy, an herbal medicine practice, uses plant extracts that are made into essential oils. While this practice may seem effective, there is no proper evidence that supports the idea (“Aromatherapy”). Most of aromatherapy’s capability comes from the human sense of smell. Inhaling the oils and fragrances through the nose allows the practice to be effective. Many people claim that by using aromatherapy as a technique it can relieve pain, promote relaxation, and have potential health benefits. For example, eucalyptus oil is a commonly used essential oil which is said to improve the immune system (“Aromatherapy”). While this may seem true, there is actually no strong evidence to prove that these oils are completely beneficial. Studies suggest that it is nearly impossible to conduct a perfect study without (Brody) other factors affecting the results. The placebo effect, in which the opinions of the participants could purely be a psychological belief (Heid), personal preferences, along with simply the types of people involved are all possible components that can affect test results (Brody). However, this does not mean aromatherapy is ineffective, it is just important to be aware of the unanswered questions (Heid). Through conducted studies, scientists suggest that claims about aromatherapy and essential oil fragrances cannot be supported as completely beneficial due to inconsistent factors.

The power of olfaction is shown through its influences on the brain and its effects on practices such as aromatherapy. Through this research, I have learned an extensive amount about the significance of the brain and the importance of maintaining proper mental health in order to improve our brain’s capacity and abilities. In an interview conducted with Dr. Eric Chudler, a professional neuroscientist, he mentioned that “Unfortunately, it is likely that we will all know someone (friend, family member) with a neurological illness or disease. By learning about the brain and how it functions, we can understand what this other person is going through and may even help with this person’s therapy.” He also explained how many significant aspects and decisions of the future such as curing diseases, advancing technology, and developing society all involve the growth of our brain (Chudler). Not only have I realized the vitality of our sense of smell and our brain, but I have now grasped a strong understanding of the role each part of our brain has and how they work together to guide us as individuals. Using this information, I hope to further educate people on properly developing the brain and promoting health and a positive mindset simply by understanding the functions of the roots of the brain. Researching this topic has inspired me to pursue a project that involves the sense of smell that is unique to each individual. I will create candles that are each different through their fragrance, and I will explore how each person reacts to the scent in a way that resembles their psychological activity. Relating the project to the research I have conducted will allow me to experiment and learn more about the brain and how it applies to each individual in our daily lives.

Works Cited

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https://link.gale.com/apps/doc/CV2191500086/SCIC?u=beav56809&sid=SCIC&xid=727

e7e5​. Accessed 6 February 2020.

Bailey, Regina. “The Olfactory System and Your Sense of Smell.” ​ThoughtCo​, 3 December

2019, ​https://www.thoughtco.com/olfactory-system-4066176​​. Accessed 2 April 2020.

Berbari, Georgina. “The Way Breathing Affects Your Brain Involves More Than Just Relaxation,

Science Says.” ​Elite Daily​, Bustle Digital Group, 24 October 2018, https://www.elitedaily.com/p/the-way-breathing-affects-your-brain-involves-more-than-relaxation-science-says-12801863​. Accessed 10 April 2020.

Brody, Jane. “Personal Health; For Aromatherapy, Big Claims, Little Proof.” ​New York

Times,​ 26 December 2000, https://www.nytimes.com/2000/12/26/health/personal-health-for-aromatherapy-big-claims-little-proof.html?searchResultPosition=1​. Accessed 18 February 2020.

Chudler, Eric. Personal Interview. 24 April 2020.

Heid, Markham.“You Asked: Does Aromatherapy Really Work?.” ​Time,​ 20 July 2016,

https://time.com/4413812/aromatherapy-essential-oils-tea-tree/​. Accessed 11 April 2020.

Marin, Allison. “Making Sense of Scents: Smell and the Brain.” ​Brain Facts​, 27 January 2015,

https://www.brainfacts.org/thinking-sensing-and-behaving/smell/2015/making-sense-of-scents-smell-and-the-brain​. Accessed 6 April 2020.

“The Smell Report.” ​Social Issues Research Centre​,

http://www.sirc.org/publik/smell_emotion.html​. Accessed 11 April 2020.