Wednesday, May 5, 2021

Smell and its Unusual Effects

  Smell, one of the five main senses, is associated with many different things. From eating food to wearing perfume, smell has a large part in the lives of many. Interestingly, research suggests that smell has several functions that many people do not think about. Several studies have shown that smell can reinforce memory in different ways. Smell can even affect creativity in some ways.

“Scents and Reminiscence: Olfactory Influences on Memory Consolidation in the Sleeping Human Brain” by Laura K. Shanahan and Jay A. Gottfried discusses several writings about how smell affects memory reactivation. The first main study Shanahan and Gottfried discussed was a study by Rasch et al. from 2007. This study was the first to research the effect of smells on memory fortification when people were sleeping. The study involved grouping a rose odor with a task where subjects attempted to learn the locations of several card pairs. After this task, the subjects slept, and the same odor was released. When the participants of the study woke up, they were asked to remember the locations of the cards from the previous task. Subjects recalled the locations better when they were exposed to the rose odor during slow-wave sleep. The researchers also concluded that the memory enhancement only worked during slow-wave sleep. Using fMRI, the researchers also found that the hippocampus was activated more during sleep when there was a presentation of the rose odor. They concluded that the hippocampus is responsive to smell during slow-wave sleep. 

The Rasch group conducted another study by Diekelmann et al. in 2011 that built on the first experiment. This experiment looked at how reactivation affected memory. The subjects participated in the same memory task as the previous study where card locations were paired with an odor, and the odor was released during sleep. Subjects then learned to link cards from learning before sleep to new locations. Subjects were lastly inquired about their ability to recall the locations of the cards before sleep. Their finding suggested that releasing the targeted odor during slow-wave sleep reinforces certain memories and prevents memory interference. 

Shanahan et al. also discuss how studies show that odors have other effects on memory, learning, and even creativity. Shanahan et al. discusses research by Ritter et al. from 2012 that investigated how olfactory targeted memory reactivation affects creativity. The researchers showed subjects a task that needed a creative solution in the presence of an odor. They then released the odor while the subjects slept. The researchers showed that the subjects who were exposed to the odor during the initial presentation of the task and during sleep came up with more creative solutions to the problem after waking. After reviewing several studies, Shanahan et al. concluded that research has shown that odors enhance declarative memories, reduce fear memories, and promote creativity.

Odors have also been shown to promote the recall of positive memories, reduce negative mood, and more (Herz 2016). Rachel Herz reviews several literature pieces that discuss odor. Hertz discussed a study by Willander and Larsson that compared memories awakened by smells, verbal labels, and smells and labels. They found that memories recalled by odors were more far more positive overall than memories evoked by just labels. Hertz discussed how Arshamian et al. showed that in adults ranging from 20 to 28 years old, odors promoted stronger and more positive memories than verbal labels. They also found that the memories evoked by odors were linked with greater activity in the temporal poles. This is significant because temporal poles have been associated with the processing of positive memories. Overall, Hertz concluded that the positive emotions brought on by odor-evoked memories can help psychological states. 

Smell has been shown to improve memory, creativity, and bring positive memories to people. This has many potential future implications. For example, pairing an odor with studying and releasing it while sleeping may improve students’ abilities to do well on tests. It also may help in different professions to illicit creativity when solving certain problems. Odors can potentially even be used to improve mental health by bringing about positive memories in people. Overall, smell has much potential to be used in many ways to improve life. 




















References

Herz, R. (2016). The Role of Odor-Evoked Memory in Psychological and Physiological Health. Brain Sciences, 6(3), 22. https://doi.org/10.3390/brainsci6030022

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 


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