Smell and Memory

The correlation between smell and memory is quite impressive. On exposure to a certain smell, many of us experience a flood of memories in the brain that are linked with distinct events or locations often associated with strong emotions. This emotional recollection of memories might be dated as far back as the early days of childhood. This miraculous ability of olfaction, also called the sense of smell, to trigger memories is mainly because of its anatomical position within the brain.

In this article, we’ll discuss how smell and memory are connected to each other in a little bit of scientific view. But before we get into the detail of how memory is associated with smell, it’s important to learn a bit more about what smell actually is and why smell is important to memory. So, let’s get started.

What is the smell?
Why smell is important to memory
The Proust phenomenon
The link between smell and memory
Final words

What is the smell?

Smell is a biological process of perceiving scents or odors in which a person sniffs through his or her nostrils to get the scent or odor of something. It’s technically known as “orthonasal olfaction”. Volatile fragrant molecules come into the nose where they reach (olfactory) receptors that lie in the nerve cells in the upper part of the nose. From those receptors, messages or olfactory signals very quickly travel to the limbic system in the brain. This way, a person can detect a scent or odor of a specified kind.

Why smell is important to memory

It’s the memory through which people learn to remember smells and you will be surprised to know that diseases that take away the capacity to distinguish smells also take away the ability to recall things that are memories. Most of these learnings begin even before people are born when they remain as fetuses in the amniotic fluid and start learning their mother’s preferences at the earliest ages of their lives.

Memories associated with visual and verbal cues often come from people’s teens or 20s, but when it comes to memories associated with smells, the peak is around the age of 5, meaning when people recollect a specific memory triggered by certain smells, that memory is often found localized to a certain period of childhood. Moreover, the smell-cued memories have been found to be more emotional and more vivid in comparison to those that are associated with visual and verbal cues.

Scientific studies also suggest that smells can represent potent triggers for memories, especially emotional ones, augmenting the capacity to recall and recognize life events. Olfaction may play an important role in stimulating the part of the brain (hippocampus) that plays a key role in regulating memory, learning, and cognitive performance.

A recent 2021 Northwestern study published in the Progress in Neurobiology showed that hippocampal connectivity in the human brain is more potent in olfaction compared to other sensory systems and there is a neural basis in the brain that enables smells to evoke powerful memories.

However, a better understanding of the correlation between smell and memory can help with promoting mental health and also managing and preventing various psychological conditions, especially those with limited treatment options like post-traumatic stress disorder.

The Proust phenomenon

“As crumbs of the madeleine cake dropped into the infusion of tisane the aroma overwhelmed me with a strange sense of joy, […] No sooner had the warm liquid, and the crumbs with it, touched my palate than a shudder ran through my whole body, and I stopped, intent upon the extraordinary changes that were taking place. An exquisite pleasure had invaded my senses, but individual, detached, with no suggestion of its origin. And at once the vicissitudes of life had become indifferent to me, its disasters innocuous, its brevity illusory, this new sensation having had on me the effect which love has of filling me with a precious essence; or rather this essence was not in me, it was myself. I had ceased now to feel mediocre, accidental, mortal. Whence could it have come to me, this all-powerful joy? I was conscious that it was connected with the taste of tea and cake, but that it infinitely transcended those savors, and could not, indeed, be of the same nature as theirs. Whence did it come? What did it signify? How could I seize upon and define it? I drank a second mouthful, in which I find nothing more than in the first, a third, which gives me rather less than the second. It is time to stop; the potion is losing its magic. It is plain that the object of my quest, the truth, lies not in the cup but in myself”

There is a range of literature on smell and memory from famous novelists such as Marcel Proust as well as others. In 1919, in his novel Swann’s Way (À la recherche du temps perdu), Marcel Proust described how a vivid childhood memory can be triggered by the flavor of a madeleine cake when dipped into a cup of tea.

Since its publication, this literary anecdote has been widely utilized by researchers to explain the fascinating way in which smell can vividly evoke autobiographical memories as a “Proust phenomenon”.

A large number of psychological and neurological studies have investigated and reviewed the Proust phenomenon on various groups of human subjects, which have led to several findings clearly confirming that smell could serve as a potential trigger to recall memories that are much more emotional than memories triggered by visual and verbal cues.

The link between smell and memory

The sense of smell is a crucial tool to predict dangers and survive in stressful situations for humans as well as other animals. With every breath, our nose constantly inspects the air around us and sends signals directly to the brain and nervous system whether we need to be more alert.

The olfactory system is located deepest in the brain and the link between smell and memory is both impressive as well as under-appreciated. An individual who experienced soothed and relaxed upon exposing certain smells in his or her childhood can continue to experience decreased stress and anxiety with those smells in his or her entire adulthood.

In the same way, smells that triggered sadness or anger in a person’s childhood can continue to evoke negative feelings in that person for years to come. Both positive and negative emotions are closely linked with memories which is why smell can trigger both positive as well as negative memories.

Smell and memory are closely connected because the parts of the brain that receive olfactory signals also store memories. This is why memories with smells are generally associated where the smell is the context or backdrop for a place, person, and any emotional state. For this reason, the sense of smell would be best connected to the memories that are often found related to specific events more specifically called episodic memories.

Final words

Smell and memory are closely correlated to each other, which is why the sense of smell often works better than the sense of sight as profound memory triggers, especially those related to childhood and vivid emotions.

Multiple studies have found that there is a close connection between smells and memories. Researchers assume that smell and memory are closely connected due to the anatomy of the brain allowing messages of the smells (olfactory signals) to get to the limbic system easily and quickly.

References:

Zhou, Guangyu, et al. “Human Hippocampal Connectivity Is Stronger in Olfaction than Other Sensory Systems.” Progress in Neurobiology, vol. 201, 1 June 2021, p. 102027, www.sciencedirect.com/science/article/pii/S0301008221000411?via%3Dihub.
Fabrice Bartolomei, Stanislas Lagarde, Samuel Médina Villalon, Aileen McGonigal, Christian G. Benar,
The “Proust phenomenon”: Odor-evoked autobiographical memories triggered by direct amygdala stimulation in humans, Cortex, Volume 90, 2017, Pages 173-175, ISSN 0010-9452, https://doi.org/10.1016/j.cortex.2016.12.005.
(https://www.sciencedirect.com/science/article/pii/S0010945216303495)
Colleen Walsh, “What the nose knows” – https://news.harvard.edu/gazette/story/2020/02/how-scent-emotion-and-memory-are-intertwined-and-exploited/