The Relationship Between Odor and Memory

 The Relationship Between Odor and Memory 

For many centuries, the connection between memory and odor has been studied through various means. A person’s sense of smell has been said to produce the most vivid forms of memory, more than visual imagery or sound. The sense of smell can have a powerful influence on the consolidation of associated memories and can clarify how sensory-rich memories are able to be stored in our brains. Studies have shown evidence for the sense of smell being highly connected to memory, in both slow-wave sleep and in Alzheimer’s Disease. 

In the study “Scents and Reminiscence: Olfactory Influences on Memory Consolidation in the Sleeping Human Brain,” Laura K. Shanahan and Jay A. Gottfried reviewed human literature on the ability of sleep-borne odors to selectively target memories, which influences both declarative and emotional memory consolidation. Shanahan and Gottfried (2017) observed a study where subjects participated in a visuospatial learning task that was paired with a rose odor. After this task, the subjects were put to sleep, and either the same rose odor or an odor vehicle was presented to them in alternation. After waking up, the researchers found that subjects performed better on the memory post-test when they were presented with the rose odor during slow-wave sleep. This finding determined that memory enhancement was specific to slow-wave sleep, and illustrated how odors amplify the consolidation of associated declarative memories during sleep. The researchers also concluded that the hippocampus was activated to a greater level when presented with the rose odor during slow-wave sleep, indicating that the hippocampus may be receptive to olfactory sensory processing. 

An article published on ScienceDaily called “Scientists uncover new connection between smell and memory,” from the University of Toronto, explains the process underlying the strong connection between memory and odor, and the loss of smell in Alzheimer’s Disease. Similar to the article from Shanahan and Gottfried (2017), the authors here say that there is a strong connection between a sense of smell and memory, and examine the hippocampus as a structure important to memory representation. In this study, researchers looked at the function of the anterior olfactory nucleus (AON) in mice. The mice with a disconnected pathway between the AON and hippocampus returned to previously smelled odors to sniff them for longer time periods. This result illustrates how the degeneration of the AON indicates an inability to detect previously observed smells. Early detection of Alzheimer’s may be more feasible now due to smell tests, although further research still needs to be conducted to perfect this. In relation to the article from Shanahan and Gottfried (2017), the emphasis on the connection between sensory olfaction and memory is highlighted, showing two different experiments where this relationship is present. Furthermore, both articles point out the fact that further research needs to be done on each respective topic regarding the relationship between olfaction and memory, suggesting that this topic is still fairly new and much more can be done to explore this connection. 

Although much more work needs to be completed to fully understand the mechanisms underlying olfactory sensation and memory, the research from Shanahan and Gottfried (2017) and the neurobiologists from the University of Toronto provide strong evidence that a person’s sense of smell is the most powerful form of memory consolidation. Even though certain findings, like the hippocampus in slow wave sleep, and the AON in Alzheimer’s patients are not fully developed yet, improvements and new technological methods can help scientists understand further processes regarding connections between olfaction and memory.

Sources: 

Gottfried, J.A., Shanahan, L.K. (2017). Scents and Reminiscence: Olfactory Influences on Memory Consolidation in the Sleeping Human Brain. Cognitive Neuroscience of Memory Consolidation, 335-346. https://doi.org./10.1007/978331945066720

University of Toronto (2018). Scientists uncover new connection between smell and memory. ScienceDaily. www.sciencedaily.com/releases/2018/07/180723155726.htm