Mmm, I know that smell!
With the current advancements in physics, time travel remains impossible. But don’t fear: our brain has come up with an adequate solution!
Have you ever taken a bite of a dish, or smelled a whiff of air that felt familiar but you couldn’t figure out where it was from?
Yet just seconds later the smell, say, for example, the mixture of aged furniture and flowers, has transported you back to a memory in your early childhood home.
If the answer is yes, that means that one, you have given chewing gum brands a new relatable ad idea, and two, that you have witnessed the freaky and completely awesome power of memory.
From remembering a phone number to childhood events, our memory is an extremely important component of who we are. Due to its wide range of roles, and the anatomical layout of the brain, scientists have been able to decode why this phenomenon of “smell nostalgia” occurs.
How do we generally remember?
In the late 1960s, renowned scientists Richard Atkinson and Richard Shiffrin identified memory as the “complex process that involves encoding, storing, and recalling information.”
To explain how these three processes are performed, they crafted the stage theory model which classified memory into three categories: sensory, short-term memory, and long-term memory.
Sensory memory is used to describe the storing of passive sensory information for ½ millisecond to 1 second, including sound, touch, image, and even language. If these details are in a zone of active awareness, then they will move on to short term memory. With continued focus or recall of these elements over time, they can move on to our long term memory.
The latter stores this information for much longer periods of time such as a whole lifetime. Long-term memory is home to explicit memories such as facts/concepts and experiences, as well as implicit memories which are actions we don’t consciously on after a period of time such as walking.
With time, this model has been adjusted and new ones have arisen. Nevertheless, it remains the basis of understanding memory.
Why is the connection between memory and scent?
Many factors contribute to our memory, with scent being one of them.
Whenever we smell something, the odor molecules enter our nose and eventually the olfactory epithelium. The epithelium is made up of olfactory receptor cells or nerves that extend cilia in the nasal cavity where they are in contact with odor molecules. These receptor cells are short-lived and replaced by the stem cells found in the epithelium.
Receptor cells are prone to identifying different types of odor molecules based on their proteins. Given the extremely diverse types of odor molecules, there is a lot of specificities when it comes to their categorization.
The information detected by cilia is then sent through the axon which lies on the opposite end of olfactory receptor cells, to the olfactory bulb, which again has subregions that specialize in specific odors. The olfactory bulb runs through the olfactory cortex in which these axons branch out.
Many axons travel to the limbic system where the amygdala, responsible for emotions, and the hippocampus, responsible for storing memory, are found. This intertwining of information is why memories are triggered when a scent is detected.
The Nobel Prize
Surprisingly, science did not a deep understanding of this connection until the early 2000s. During this time, researchers Richard Axel and Linda Buck published much of their groundbreaking work on how the brain perceives smell and translates it to behavior. They were able to detect thousands of genes responsible for odor recognition as well as map the path signals detected that follow through the brain. These discoveries kickstarted a whole new era of research into the physiological understanding of smell.
Because of their astounding work, they were both rewarded the 2004 Nobel Prize in Physiology or Medicine.
Conclusion
Every bit of our experiences is connected to our perception of the world and together make up a great amount of who we are. Elements such as smell and taste, are perfect examples of this.
So every time you pass smell something familiar, you have your hall of memories to thank.
Key-Takeaways
- Smells can trigger memories collected throughout our lives
- Smells travel through an olfactory pathway which identifies specific odors
- This pathway leads synapses which contain this information to travel to the hippocampus and amygdala that are responsible for the intertwining of smell and memory
References
- https://news.harvard.edu/gazette/story/2020/02/how-scent-emotion-and-memory-are-intertwined-and-exploited/#:~:text=Smells%20are%20handled%20by%20the,related%20to%20emotion%20and%20memory.
- https://lesley.edu/article/stages-of-memory
- https://www.nobelprize.org/prizes/medicine/2004/buck/lecture/
- https://app.nova.edu/toolbox/instructionalproducts/edd8124/articles/1968-Atkinson_and_Shiffrin.pdf
*Other resources used have been embedded in the text.*