Why Do Certain Smells Trigger Powerful Memories?

You're patiently waiting in line at the grocery store cash counter when the smell of freshly baked choco-chip cookies excite your olfactory senses. The presumably soothing scent—infused with notes of sweet vanilla—take you back to a cherished childhood memory, enveloping you in glee. Although, just a minute later, the fleeting emotions fade. 

Your brain: WHAT IN THE WORLD WAS THAT? 

The thing is: Odours often evoke vivid memories, taking a direct route to the limbic system, including the amygdala and the hippocampus, suggesting that scent, memory, and emotion are intertwined. 'Our memory is controlled by the limbic system of the brain, and all sensations—visual, auditory, gustatory, tactile, and olfactory—are stored in the association areas. Hence, whenever an event is in reference to the memories of the association area, one gets reminded of an experience that took place previously,' explains Dr Vinit Suri, Senior Consultant, Neurology, Indraprastha Apollo Hospitals.

Sanjoni Sethi, Psychologist and M.Phil Scholar, adds, 'When an odour occurs, emotional experience and meaning may be associated with the scent. This form of association comes from learning principles. Thus, a specific odour related to an individual’s experience becomes part of the autobiographical memory schemas. Smell elicited memories are known to uplift moods when compared to memories evoked by another sensory modality. Aromas that trigger specific personal memory such as nostalgic memory arouse feelings of happiness, optimism, and joy. On the other hand, researchers have found that negative emotions are particularly associated with the smell of a specific material—such as diesel or petrol—for individuals who have undergone traumatic events related to such materials (for instance, a car accident).'

Although, scent memories are found to be more powerful, as compared to those triggered by our other senses. Here's why: 'The olfactory bulb has a direct connection with the limbic system, making smell an important sensory modality that can be instantly linked to previous memories. Plus, the limbic system contains information related to moods as well,' puts forth Dr Suri. 

In conclusion, scientists believe that the brain regions accountable for the processes of memory, emotion, and smell functions (commonly known as olfactory sense) work hand-in-hand. The three brain regions are responsible for associating a smell with certain emotions and bringing back a particular memory, as the process is intertwined. A recent study published in Progress in Neurobiology explores the power of scent in triggering memories, indicating that this ability comes from the connection between the olfactory system and the hippocampus in the brain.