Wednesday, May 1, 2019

Scent and Memory: A step deeper into recollection

Often times, returning to certain locations will bring about a flood of memories. Certain locations may be places that an individual visits often, like their workplace or home, but other locations can be places visited minimal times, such as particular restaurants or vacation spots. However, no matter how many times a location was visited, individuals are more likely than not to remember the exact events that unfolded in those locations upon revisiting or even seeing pictures of the place. In Dr. Melissa Hebscher’s talk, she discussed that in order to retrieve a memory, an individual “must recall the spatial context” before they even begin to remember how things played out. She explained how the precuneus, a structure located near the medial parietal lobe, plays a role in the vividness, imagery, and spatial processing of memories. She stated that individuals who remembered people in certain settings while attempting to retrieve a memory had larger precuneus volumes than those who did not. Dr. Hebscher emphasized how retrieval of memories is largely dependent on the ability to spatial reconstruct a scene of that memory.
However, it turns out that the sense of smell has also been found to play a large role in memory and memory recollection. Similar to spatial locations and memory, certain smells will bring people to remember past experiences in their lives. According to a study done at the University of Toronto, it was found that the “strong connection between memory and olfaction” results in “smells [that] we've encountered in our lives are recreated in memory.” More often than not, individuals find themselves reminiscing when they smell certain perfumes worn by significant others, scents of food associated with family members or gatherings, and so on. Not only have University of Toronto neurobiologists found this connection between memory and scent, but they also found that “space and time integrate within a region of the brain important for the sense of smell -- yet poorly understood -- known as the anterior olfactory nucleus (AON)” and furthermore found the association between the AON and the hippocampus and how they can track this memory network in helping to diagnose Alzheimer's early on. Although not much is known about the AON, it is “among the earliest sites of neurodegeneration including the formation of neurofibrillary tangles, which are abnormal proteins found in Alzheimer's patients.” The fact that neurobiologists at the University of Toronto were able to recognize the AON and its role in scent and memory and connections to the hippocampus results in a lot of promise in the development of tests that can potentially help diagnose Alzheimer's in the very early stages, which can help individuals diagnosed with the disease receive more treatment and manage it better over time.
Another study done at McGill University highlighted the association with spatial memory and sense of smell. During their study, they tested participants’ spatial memory by having them navigate through a virtual city while paying attention to landmarks and then having them propose routes through the city to get to landmarks; they also tested their sense of smell by having them identify 40 scents, ranging from different types of spices to different types of fruits. What researchers at McGill University found, was that “people who have better spatial memory are also better at identifying odors.” This allowed the researchers to come to the conclusion that both spatial memory mechanisms and olfactory mechanisms “seem to rely on similar brain regions supports [and are] systems in the brain that were evolving at the same time.”
Overall, perhaps the most common ways of recollecting certain experiences from the past have to do with being able to spatially recognize the location in which the event happened and also smelling the same scent that was present during that time. Research done at McGill University helped emphasize the relationship between spatial recollection and the olfactory system and how both functions seem to be related in memory recall. Additionally, the work done at the University of Toronto helped to highlight the relationship between smell and memory and the possible connection to using the olfactory system and its effectiveness in diagnosing Alzheimer's disease in its earliest stages.

References:

Hebscher, Melissa. “Neural Correlates of Spatial Representations in Autobiographical Memory.” Neuroscience Seminar. 19 Feb. 2019, Loyola University Chicago.

McGill University. "Good spatial memory? You're likely to be good at identifying smells too: Similar regions of the brain are involved in both cases." ScienceDaily. ScienceDaily, 19 October 2018. <www.sciencedaily.com/releases/2018/10/181019120728.htm>.

University of Toronto. "Scientists uncover new connection between smell and memory: Findings offer opportunities for improved smell tests in Alzheimer's disease diagnosis." ScienceDaily. ScienceDaily, 23 July 2018. <www.sciencedaily.com/releases/2018/07/180723155726.htm>.

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