Have you ever caught a smell and instantly you can start remembering the first time you experienced the smell, or perhaps a period in your life with a distinct visual memory? Well, as it turns out there is a strong connection between the human olfactory and memory system.
Researchers at the University of Toronto have found that the region of the brain that stores information based on space and time integrates with the same region of the brain that is important for the sense of smell known as the anterior olfactory nucleus (AON). When this information combines in the brain, a memory is formed, and this process is called an episodic memory. While researching this connection, the researchers discovered a new neural pathway between the AON and the hippocampus, which also happens to be highly impacted in Alzheimer’s patients. Interestingly enough, patients with Alzheimer’s are commonly found to have lost their sense of smell, thus providing more evidence for its connection and impact on memory loss in Alzheimer’s patients. Without smell, these memories cannot be triggered.
This pathway is fascinating as it can be used a potential screening for early diagnosis of Alzheimer’s disease. There has been some shift in focus to creating smell tests that can target this neural connection in the brain. Thus providing affordable and non-invasive detection measures that can be used for these patients for early diagnosis.
Aqrabawi, A. J., & Kim, J. C. (2018). Hippocampal projections to the anterior olfactory nucleus differentially convey spatiotemporal information during episodic odor memory. Nature Communications, 9(1). doi:10.1038/s41467-018-05131-6
I had never really understood the anatomy or physiology behind how a certain smell could elicit such a distinct memory, but after your explanation this phenomenon, it makes total sense. While there are probably hundreds of millions of different smells out there, if not more, it is fascinating to me that our AON can distinguish between them and spawn new memories that are formed in the hippocampus. Your further mention of how this can be vital to the diagnosis of Alzheimer's, is fascinating and proposes further questions as to how the sense of smell can be related to memory construction or loss. With that being said, did you find any research on the biochemical aspects of the loss of smell and how it relates to a possible Alzheimer's diagnosis via smell tests and memory formation and recollection?
ReplyDeleteBeyond experiencing this phenomenon myself, I also saw the way smells, music, and tastes stirred up memories in my grandmother who was suffering from dementia up until the last few months. I think this is an amazing discovery into understanding the human brain its many different pathways. Upon reading your post it makes sense to me based on what we have learned in school that the AON would have a pathway with the hippocampus, since the hippocampus is responsible for our memories. This also gives me further hope that in research we can develop more testing methods and understanding out the diseases that come with age and brain injuries. In consideration of your post could the loss of smell lead to diagnosis concerning other diseases/ conditions beyond Alzheimer's?
ReplyDeleteHi Brittney! Cool post! I remember learning about how our sense of smell is linked to our memory in high school! Interesting how one whiff of something can take us back to an old memory...
ReplyDeleteI found an article talking about how these two are regulated and how they might have the ability to increase positive emotions, decrease negative mood states, disrupt cravings, and reduce physiological indices of stress (Herz et al., 2016). As you focused on Alzheimer's and other neurological disorders, I wonder if this can also help with depression and bipolar disorders...
Interesting stuff!
Herz R. S. (2016). The Role of Odor-Evoked Memory in Psychological and Physiological Health. Brain sciences, 6(3), 22. https://doi.org/10.3390/brainsci6030022