Olfactory plays a big role in everyday life because the olfactory process can be used for different reasons and it is used unconsciously sometimes. For example, people can use their olfactory process to smell food and be able to tell whether the food has spoiled or not in order to avoid getting sick. It can also be used to smell different items that may have had some significant meaning to the person and it can bring back memories of the event the smell is associated with and it may be used to enhance people’s appetite because talking from experience when I smell something delicious, I get an appetite for the smell and then the food that the smell is coming from compels me to eat it.
Furthermore, the olfactory can also be used to enhance cognition and memory and it can be seen in both humans and animals through different learning tasks. One specific example of a study that discusses the use of olfactory and its impact on memory is a research article done by Laura K. Shanahan et al. called Scents and Reminiscence: Olfactory Influences on Memory Consolidation in the Sleeping Human Brain. In the article, the team of researchers wanted to discuss all of the relevant research that was done on the relationship between using odors on the sleeping brain and memory consolidation as well as discuss the implications of each study. Some of the research that was talked about in this article was an expansion from the first formal study which was on the topic of how odors can influence memory consolidation during human sleep and this study was conducted by Rasch et al. In the study, the researchers used phenylethyl alcohol which gives off a rose odor and they paired it with a visuospatial learning task where the participants learned the location of several card pairing. Additionally, the same group of researchers did a follow-up experiment where they used functional magnetic resonance imaging (fMRI) which was used to investigate hippocampal activation during the odor reactivation task. In addition, at the end of the study, the researchers determined that further research was needed to determine that targeted memory reactivation (TMR) actually evoked memory replay during sleep. Moreover, Rasch et al. conducted a second olfactory TMR study that looked into the role of reactivation in a memory paradigm incorporating memory interference. The researchers concluded this study that further research would be needed to determine whether changes in brain activity during olfactory TMR were predictive of subsequent targeted changes in the memory performance. Additionally, Dickelmann et al. conducted an olfactory TMR study in order to determine the extent to which sleep with reactivation had a greater impact on subsequent memory performance than sleep per se. However, an implication that was addressed by Laura Shanahan et al., is that each of the studies talked about used the same card location memory paradigm which led to questions of the generalizability of the results. Also, in order to address the question of generalizability of the results. Cox et al., decided to conduct an olfactory TMR study using a unique memory paradigm that involved a word location association task. In this study, the participants learned to associate words with particular locations on a screen in the presence of two distinct odors. However, an implication of this study was that it was not possible to draw any conclusions about the relationship between the amount of local spindle activity and memory outcomes due to the reactivation not resulting in enhanced memory performance for targeted word locations. Furthermore, Laura Shanahan et al. went a step further and talked about the fear conditioning paradigm which about how Hauner et al. utilized olfactory TMR to modulate emotional memory consolidation during slow-wave sleep. In this study, the participants learned to associate pictures of two faces with electrical shocks which were in the presence of two distinct contextual odors during fMRI scanning.
In addition to the research discussed by Laura K. Shanahan et al., another study that studied the topic of memory and the use of olfactory was a study done by Zhiwen Gong et al., called Floral Tea Polyphenols can Improve Honey Bee Memory Retention and Olfactory Sensitivity. In the study, the team of researchers performed three experiments where the first experiment, the team of researchers tested the natural percentage of caffeine and tea polyphenols that was produced from the Camilla sinensis tea nectar. Furthermore, this led the researchers to create a synthetic solution of tea polyphenols which contained around the same proportions of each tea polyphenol compound which excluded caffeine. The second experiment was where the researchers trained the Apis mellifera which are better known as the Western honey bees to forage for food. Furthermore, the honey bees had three different feeder choices where each of the feeders had different tea polyphenol concentrations and the researchers scored the feeder choice only if the bee was feeding on it for more than 10 seconds. The third experiment that was done was where the researchers wanted to test learning and memory in honey bees and they did this by training the honey bees by lightly tapping on one of the antennas with the unconditioned stimulus to elicit PER and then the bees were allowed to feed. Also, during the memory tests, the researchers exposed the trained bees at each memory test time point to the conditioned stimulus alone which was hexane, or to the novel odor which was nonanal, and the bees were not rewarded during the testing stage. Moreover, the fourth experiment that was done was to test if the tea polyphenol could influence the honey bees' antennal response to alarm pheromone compounds. In addition, the researchers recorded each bee via electroantennography (EAG) and all the bees during EAG gave off the same primary alarm compounds in their sting alarm pheromone which were isopentyl acetate, octyl acetate, and benzyl acetate.
In regards to the studies talked about in this paper, both studies showed the benefits of using olfactory in order to test memory for both bees and humans. However, in the article by Laura K. Shanahan et al.. the main focus of the studies discussed was using different odors such as rose or banana on human participants to test learning and memory through a card memory location task. While the article by Zhiwen Gong et al., focused mainly on using the feeder with the different tea polyphenol concentration levels to test memory in bees. The reason why people should pay attention to this topic of using the olfactory to improve memory and cognition is because it could possibly be the next revolutionary thing that could benefit everyone. For example, it could be used to help people relive a memory that they cherished in the past and it can also be used to help people with a small degree of lesions to their hippocampus to remember certain things. It can be used possibly to help students study for their exams and get better grades which will possibly lead the students in the future to do more research on the topic of olfactory thus helping everyone further. Overall, the topic of olfactory is very useful to everyone in their everyday lives and I believe that with more research being done on this topic, it can lead to more advanced ways that could possibly help to save someone’s life or even improve their life for the better.
References:
Gong, Zhiwen et al. (2021). Floral Tea Polyphenols can Improve Honey Bee Memory Retention and Olfactory Sensitivity. Journal of Insect Physiology. https://doi.org/10.1016/j.jinsphys.2020.104177
Shanahan, Laura K. et al. (2017). Scents and Reminiscence: Olfactory Influences on Memory Consolidation in the Sleeping Human Brain. 10.1007/978-3-319-45066-7_20
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