By Danielle E. Jennings

Danielle received her B.S. in developmental psychology from Plymouth State University ’16, and is currently working on her master’s degree in psychology at Rhode Island College. She currently works as a Milieu Therapist at Bradley Hospital in the children’s inpatient unit. Danielle’s primary research interests lie in health and developmental psychology, and specifically in research on neurodevelopmental disorders. For the past semester, Danielle has worked as a graduate teaching assistant in Dr. Smith’s Brain/Cognition lab.

Imagine you come back to your hometown after moving away ten years ago, and you visit your favorite coffee shop that you went to nearly every day in high school. If it’s a good coffee shop, and you haven’t been there in some time, odds are you’ll be overwhelmed with the smells of fresh ground coffee and other treats. However, suddenly you feel a rush of memories from the years you spent here. Some are specific and detailed, of the times you spent in class on the athletic field or just times you met friends, while others are jumbled. You also feel a rush of positive or negative emotions connected to these memories.  These are things you wouldn’t normally think about, so is your olfactory bulb playing tricks on you?

Sense of smell: a trigger for memory and emotion

The olfactory bulb, responsible for processing smell, is located in the forebrain. However, it starts with odor molecules, from something like food, traveling through the air where they are taken in by the nostrils. The odor molecules first meet chemoreptors located behind the eyes, which detect the presence of external stimuli (1; for a brief crash course on taste and smell, see this video). Next, the signals are sent to multiple areas in the brain after interacting with the olfactory cortex. Some signals are sent to the frontal lobe where the odors are individually identified, while other signals are sent to the limbic system which includes the hippocampus and amygdala (2). Because of these anatomical connections, smell is able to trigger memories, and amazingly, the olfactory bulb is the only structure related to the five senses that is connected to these areas responsible for emotion and memory (2).

Lose your sense of smell, lose your memories?

The sense of smell can also have negative implications for memory and emotions. On a medical level, there are many cases, such as head trauma, sickness, diabetes, and vitamin deficiency that can lead to the development of anosmia. Anosmia is when one loses their sense of smell, and as a result one’s sense of taste as well (3). In very extreme cases called congenital ansomia a person can be born without a sense of smell. Some may think that not being able to smell certain things such as garbage and dirty diapers would be beneficial, but those who do lose their sense of smell may experience depression. Anosmics “are deprived of the pleasure of eating and drinking” (4) and this lack of sensory experience greatly decreases one’s life experience. When they walk into the coffee shop that I mentioned earlier, an anosmic individual wouldn’t be reminded of their experiences associated with the smell. The most depressing part may be that they cannot differentiate a freshly baked cookie from a brussel sprout. 

Our sense of smell and memory can also trigger negative emotions in relation to PTSD. A study by Vermetten and Bremner (5) examined 3 cases of soldiers diagnosed with PTSD. After smelling diesel, one patient stated that he often experienced feelings of guilt, helplessness, nausea and memories of “an accident in Vietnam. In his mind he could vividly see the burning vehicle, doors ajar, and billows of fire and smoke” (5). Smell is an extremely important sense in our daily lives; however even more so, is it subliminally based in our survival.

The nose, knows

Past research on the olfactory system has been primarily focused on how our sense of smell is linked to our episodic memory and the recognition of previously learned smells, and how we can “smell up” memories from high school just from the scent of a coffee house. However, since we know that learning comes from our ability to retain and recall information with the help of our memory system, then what about utilizing our sense of smell to help us remember the facts we learned for a big exam?  While present day research on the sense of smell and learning improvement is scarce, it does exist.

 Aromatherapy is an ancient alternative healing remedy that uses fragrant essential oils in an attempt to prevent illnesses and change people’s emotional states. A research group in Pakistan was interested in whether different aromas could be used to increase cognitive learning, memory and attention in the classroom (6). It is believed that certain smells effect different brain functions and physiological states. For example, lavender is said to create a calming sensation in an individual, while citrus scents are said to help improve focus, attention, and energy. The previously mentioned study found that when a lemon scented aroma was introduced to one classroom, but not the other, the students in the classroom with the aroma stimulus did display an improvement in their cognitive performance and ability to remain attentive during learning (6). So, can we conclude that we will get better grades by smelling lemons while we shuffle through our flashcards? Not necessarily. However, the results from this study may indicate that an aroma stimulus may improve learning when paired with visual stimulus like a PowerPoint, and an auditory stimulus like a lecturer speaking. The added aromatic arousal might increase our attentiveness, thus increasing the effectiveness of our visual and auditory systems in a learning environment (6). But clearly, this finding is a lot more controversial than the decades of research on effective study strategies! Take these findings with a grain of salt – or perhaps, a whiff of lavender.

References:

(1) Taste & Smell: Crash Course A&P #16 (2015, April 27). Retrieved from https://www.youtube.com/watch?v=mFm3yA1nslE

(2) Gaines, J. (2015, January 12). Smells ring Bells: How smell triggers memories and emotion. Psychology Today. Retrieved from https://www.psychologytoday.com/blog/brain-babble/201501/smells-ring-bells-how-smell-triggers-memories-and-emotions

(3) Blodgett, B. (2016, November 17). Anosmia: The quiet killer. The Huffington Post. Retrieved from http://www.huffingtonpost.com/bonnie-blodgett/anosmia-the-quiet-killer_b_648971.html

(4) New Scientist (2013, April 27). Losing your sense of smell. How bad can it be? New Scientist. Retrieved from https://www.newscientist.com/article/mg21829143.100-losing-your-sense-of-smell-how-bad-can-it-be/

(5) Vermetten, E., & Bremner, J. D. (2003). Olfaction as a traumatic reminder in posttraumatic stress disorder: Case reports and review. Journal of Clinical Psychiatry, 64, 202-207.

(6) Akpinar, B. (2005). The role of sense of smell in learning and the effects of aroma in cognitive learning. Pakistan Journal of Social Science, 3, 952-960.