Smell and Memories - Sense Week


Photo courtesy of Wikimedia Commons.

Everybody has photos they enjoy looking at to bring them back to a time gone by. There are also those songs that transport them to events that took place years back (see what happens when you play Sisqo’s “Thong Song”). However, photos and songs pale in comparison to the capabilities that smells have in triggering memories.

Picture this scenario: A young gentleman named Calvin is walking down the street and a girl passes by in the opposite direction wearing Chanel No. 5. As soon as he picks up the scent of the aroma, he has a flashback of an ex-girlfriend that wore the same fragrance. He might not have thought about this woman in years, but the whiff of sweet essence brings back thoughts in vivid detail of the long-gone relationship.

The relationship between smell and memory is complex and scientists do not know the exact reason why the two are linked so closely, but there are many accepted factors to explain the parallel.

When Calvin walked by the girl wearing Chanel, the molecules of the scent traveled into his nose and hit the smell receptors. These receptors have a direct connection to the olfactory bulb, the area in the brain that processes smells. The process is similar to the ways our other senses are interpreted, but where smell differs is that it has a direct connection to the brain.

When he saw the girl walking towards him and heard her heels clicking on the ground, her image and sound was recorded by the eyes and ears, then sent to the thalamus which takes in what is being processed and then sends these signals to the other areas of the brain that interprets what he is sensing. This complex group of highways is quite different than the one-way street that smells travel to the olfactory bulb, creating what is thought to be a more powerful sensation.

The olfactory bulb is part of the limbic system which has also been called the “emotional brain” since it is closely connected with memories and the feelings a person experiences. Lying next to the bulb is the area where associated learning takes place called the hippocampus and the area that processes emotions, called the amygdala. Both of which are also parts of the limbic system. The proximity of the olfactory bulb to these areas of the brain is believed to be one of the fundamental reasons memories and smells are connected.

Every time a new smell is processed in the brain, a new connection is developed between what is being smelled and what is associated with it. Calvin first smelled the perfume on his ex-girlfriend which created a link between her and the smell. When the new girl walks by him, the hippocampus fires the connection that it originally associated with the ex-girlfriend. This connection is a form of survival mechanism.

As a child, Calvin was exposed to countless new smells that were constantly creating new connections in the brain. If he smells rotten food for the first time, he will then associate this scent with food to stay away from later down the line. This is the same case for our ancestors if they were to smell a predator in the vicinity or a fire nearby.

Once the brain connects a new smell to a memory, the link between the two stays the same as people get older. This is why many scents bring back nostalgic memories of being young because the first time many people are exposed to new smells are at a young age.

One experiment that supports this fact was conducted in Sweden. A group of people with an average age of 75 were given twenty memory cues in three different forms. This consisted of a word, picture and a smell. The group was then told to give an association with each cue. The majority of the associations for the words and pictures came from when the study group was in their teens to twenties, while the scent cues brought back memories from age ten and younger.

The nostalgic feeling that comes from smells provides more uses than bringing up memories and survival. Scent marketing is a growing trend among businesses. The real estate industry capitalizes on this by placing freshly baked cookies or pies in houses for sale to bring a comfortable atmosphere to the environment. Other businesses use more subtle scents to bring ease to their potential customers. They might not be able to tell if they smell anything, but it is enough for the olfactory bulb to receive the scent which then allows marketers to cash in on the nostalgic connections stored in the brain.

Israeli scientists are also finding practical uses with scent by researching ways to use these connections as a way to treat trauma patients. Calling it “smell therapy” they are developing techniques that would take the connections with scents – either good or bad – and assisting in bringing back memories or potentially erase traumatic events from the mind altogether.

There is still plenty to unlock in the process of demystifying the gray matter that lies between our ears. More information explaining why scent and memory are a package deal may lie on the horizon along with different ways to utilize this phenomenon. In the meantime, Calvin will continue to enjoy the brief moments where he gets flashbacks of lost love.