Fragrant Flashbacks: Why Smell Triggers Memories

Smells can elicit strong emotions. A passing whiff of perfume could conjure up memories of an old buddy, while the aroma of food cooking on the stove could transport you to your grandmother's kitchen. Scent particles, in general, can revive memories that have been long forgotten. Researchers reveal how human evolution and brain wiring may help to explain how odors may elicit such vivid memories in a new study published in Progress in Neurobiology.

But why do smells sometimes trigger powerful memories, especially emotional ones?

The short explanation is that the parts of the brain that deal with scents, memories, and emotions are all linked together. In fact, your sense of smell is the only one of your senses that is tied to your brain in this way. A fragrance is a chemical particle that enters through the nose and travels to the brain's olfactory bulbs, where it is processed into a form that the brain can understand. The information is subsequently carried by brain cells to the amygdala, a small portion of the brain where emotions are processed, and then to the hippocampus, where learning and memory are formed.

Scents are the only sensations that move so quickly to the brain's emotional and memory regions. All other senses pass through the thalamus, a brain region that functions as a "switchboard," transmitting information about what we see, hear, and feel to the rest of the brain, according to John McGann, an Associate professor at Rutgers University in New Jersey's psychology department. Scents, on the other hand, bypass the thalamus and reach the amygdala and hippocampus in a "synapse or two," according to him.

As a result, emotions, memories, and fragrances become inextricably linked. This is why memories produced by scents are "perceived as more emotive and evocative" than memories triggered by other senses, according to Rachel Herz, author of "The Scent of Desire" and adjunct assistant professor of psychiatry and human behavior at Brown University in Rhode Island (Harper Perennial, 2018). She went on to say that a familiar but long-forgotten aroma might even drive people to tears.

The Emotion of Scent

Scents are "really special" because "they can bring back memories that might otherwise never be recalled," Herz said. In contrast, seeing familiar individuals and places on a daily basis will not jog your memory of specific events. Walking into your living room, for example, is a repetitive stimulus, something you do over and over again, thus it's unlikely that the activity will trigger memories of a specific event that occurred in that room. On the other hand, "if there's a smell that's connected to something that happened way in your past and you never run into that smell again, you may never remember what that thing was," Herz added.

When a person smells something that reminds them of a significant event in their history, they are likely to have an emotional reaction first, followed by a recollection. However, occasionally the memory won't come back; the individual may feel the feeling of something that happened in the past but won't recall what happened, according to Herz. "And this is unlike any of our other sensory experiences," she added. To put it another way, you wouldn't see something and experience emotion but be unable to recollect the memories associated with that sight and sensation.

This is partly due to the circumstances. Imagine someone going down the street and experiencing an emotional reaction to a scent they originally encountered decades ago. It will be far more difficult for them to recall the linked memory if they first encountered that smell in a very different situation, such as a movie theater. According to Herz, the brain uses context "to give meaning to the information" and locate that memory.

If a person smells a scent repeatedly, the scent will detach from a specific memory and lose its ability to bring that memory back, she explained. Furthermore, memories recalled by fragrance share the same flaws as other memories in that they might be erroneous and overwritten with each memory. People who recall something because of a certain scent are often sure that their memories are correct, Herz said, because of the strong emotional links these memories create.

The link between fragrance and memory extends to memory-related health problems as well. A loss of sense of smell can be an early indicator of memory-related diseases including Parkinson's disease and Alzheimer's disease, but it can also be a result of aging, according to McGann.

This unusual intertwining of emotions and fragrances could have a straightforward evolutionary basis. According to Herz, the amygdala originated from a brain area that was originally specialized in detecting substances. "Emotions tell us about approaching things and avoiding things, and that's exactly what the sense of smell does too," she said. "So, they're both very intimately connected to our survival."

In fact, the way people utilize emotions to perceive and respond to the world is similar to how animals use their sense of smell. So, the next time a whiff of perfume brings you to tears or a huge smile runs over your face when you smell baked pie, you may credit, or blame, the way your brain arranges information on an ancient scaffold.

Source: livescience.com

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Maina Zaina, Writer and a Virtual Assistant at AVCreativity Studio. She enjoys media entertainment and is an avid fan of "K-Wave". She loves her job because she is exposed to different types of entertainment. She also believes in the saying "If you want to be successful, don't seek success - seek competence, empowerment; do nothing short of the best that you can do" by Jaggi Vasudev

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