Smell and Its Effect On Memory

               

    When it comes to memory, many of us would assume that senses such as sight, sound, and touch would have the most eminent role in the formation of memory as those are some of the most common senses used in our daily live. We see the morning sun rise, we hear the birds chirping, and we touch our loved ones to show affection. However, a sense that also plays a large role in memory is one that comes to a surprise to some-smell. Indeed, smell, or rather olfaction, has a prominent role in the formation and consolidation of memory in the human brain. It is evident that over the millennia, Man has become more and more visually adapted given our extensive use of visual based devices such as screens, but the importance of the other sense, namely smell, should not be disregarded. Researchers have been working away to uncover the nature of this sense and the effects that it has on memory and the results are rather profound.

               Olfaction would have itself play a broader and deeper role in memory than one would think. Dr. Laura K. Shanahan reports that researchers, such as Dr. Rasch, have been investigating the role that olfaction plays in the formation of memory.  The experiment itself consisted of a visual/spatial learning task that involved the participants learning where certain card pairs were located. The participants were then instructed to go to sleep and upon waking, were tasked with recollecting the card pairs. While asleep, the experimental group was exposed to a rose aroma while they slept. Results from this experiment demonstrated that during slow wave sleep, participants exposed to the odor did better in the recollection than those that were not exposed. An fMRI that was conducted in a related experiment revealed how the hippocampus becomes active and receptive to olfaction during slow wave sleep and thus explains how the participants did better in the task. This experiment marks how odor plays a key role in forming stronger memory connections. While humans have clearly demonstrated the importance of olfaction in the formation of memory, the effect is more pronounced in those animals.

               Dr. Shanahan and Rasch were not the only one investigating the role that olfaction plays in the formation of memories, but also individuals such as Dr. Strauch and Manahan-Vaughan were also investigating the role that olfaction plays in memory. The experiment was conducted on rats who have had direct neural stimulation of the piriform cortex and simulated sets of different neural impulses. The impulses are used to essentially simulate different instances of odor that have been perceived by the rat and so would give an idea of how the brain of the rat would react. The testing found that different paths were activated when neurons were stimulated in both the hippocampus and the piriform cortex. The results of the experiment demonstrated that the piriform cortex, which is a part of the brain that concerns olfaction, has influence on the information storage within the hippocampus. Animals have a clear connection between the olfactory neurons and memory, just as humans do. Perhaps looking into the olfactory nerves of animals will also paint a better picture of how it affects us as well.

               A good way to visualize all this data is to try to remember personal memories. Recall a memory, a pleasant one perhaps. Remember the sights and sounds that day, the feelings of joy and jubilation. Then it hits you. The smells of that time, the mood in the air as well. It permeates the memory and creates with it a masterpiece. That is the power that smell has on memory. An even more obvious example would be smells associated with festivities such as the smoke of a summer barbecue or a welcoming aroma of a Christmas candle. Strong memories such as the aforementioned are more strongly tied to a particular sent and provide for a stronger memory. From this little thought experiment, smell indeed does invoke powerful memories and leads to a stronger retrieval of those memories than some other stimuli.

               Of course, there is still much to learn in the realm of Memory Formation. In time, future advancements in technology and advancements in research techniques will enable a better grasp on the mechanisms behind the process itself and could lead to new realm of learning in turn. The sense of smell may not seem much to many, but its role in memory consolidation has demonstrated itself to be an important addition to the human experience. Now, with a better understanding of the sense of smell, perhaps it is a good idea to take note of the sense and the sensations that it brings. Follow your nose, there may be some pleasant memories to be made in that sweet smell of fresh baked bread that you just picked up.

 

References:

Shanahan, L. K., & Gottfried, J. A. (2017). Scents and Reminiscence: Olfactory Influences on Memory Consolidation in the Sleeping Human Brain. Cognitive Neuroscience of Memory Consolidation, 335–346. https://doi.org/10.1007/978-3-319-45066-7_20

 

ScienceDaily. (2019, April 29). How the olfactory brain affects memory. ScienceDaily. https://www.sciencedaily.com/releases/2019/04/190429125422.htm.