If you haven’t read my first blog post titled ‘Smemories- Part 1 ‘ don’t fear, because in this blog posts i will be looking at how the human sense of smell triggers memories from our past. I will be doing this by asking a series of questions, that i will be answering using scientific explanations.
Hopefully by the end of this blog post, you and i (if not already), will both have an understanding of the science behind all of this.
How do we smell?
The anatomy of the human nose is the key to this question!
As we smell, molecules emitting from a substance, in this case the banana, travel through the air and into the nose. The air containing the molecules enter the nose through the nostrils (Silverstein, Silverstein, & Nunn, 2002).
Once in the nose, the molecules further travel into a thin layer of membrane known as the Olfactory. This membrane is located at the top of the nasal cavity, its surface is lined with a thick layer of mucous (Silverstein, Silverstein, & Nunn, 2002).
Within the Olfactory membrane “hair-like” projections, which are refereed to as Olfactory receptor cells (or nerves) extend into the mucous layer. Each one of these receptor cells are sensitive to a particular molecule (Vokshoor , 2013).
The “correct” molecule attaches itself to its corresponding receptor cell, almost like a-lock-and-key (Vokshoor , 2013).
As a result of the binding, nerve impulses are transmitted to the Olfactory bulb. It is here where the smell is analyzed by the brain, and further transmitted to the other parts of the brain via two pathways:
Pathway 1– nerve impulses are transmitted to the frontal cortex (frontal lobe) of the brain, resulting in the smell being consciously identified.
Pathway 2– impulses are transmitted to a set of neurons known as the Hippocampus, which make up a part of the limbic system responsible for long-term memory storage, and retrieval (Goodrich-Hunsaker, Gilbert, & Hopkins, 2009).
A study that was conducted by Ryan, L, & his colleagues at the University of Arozona, found that the Hippocampus is responsible for the retrieval of short-term, and long-term autobiographical memories. The study was carried out using functional magnetic resonance imaging (FMRI). Subjects who had functioning brain activity were asked to recall vivid memories that had occurred within the last four years, or more than 20 years ago. In recalling memories, the FMRI showed that the Hippocampus was activated in all the subjects, for both conditions.
How does smell trigger memory?
The area in the brain responsible for smell and memory are closely related due to their locations. The Olfactory bulb, the smell analyzing region, is connected to the Hippocampus, an area associated with memory. The Hippocampus receives incoming information from all areas of the brain. It is possible that a certain scent maybe associated with a certain memory (Goodrich-Hunsaker, Gilbert, & Hopkins, 2009).
Goodrich-Hunsaker, N. J., Gilbert, P. E., & Hopkins, R. O. (2009). The role of the human hippocampus in odor-place associative memory. Chemical Senses, 34(6), 513-521, <http://eds.b.ebscohost.com.ezproxy-f.deakin.edu.au/eds/pdfviewer/pdfviewer?sid=4af4bf46-553d-425f-85f2-2d1d60b0e5d9%40sessionmgr104&vid=13&hid=122>.
Jacobs, N. S., Allen, T. A., Nguyen, N., & Fortin, N. J. (2013). Critical role of the hippocampus in memory for elapsed time. The Journal Of Neuroscience: The Official Journal Of The Society For Neuroscience, 33(34), <http://eds.b.ebscohost.com.ezproxy-f.deakin.edu.au/eds/detail/detail?vid=9&sid=4af4bf46-553d-425f-85f2-2d1d60b0e5d9%40sessionmgr104&hid=122&bdata=JnNpdGU9ZWRzLWxpdmUmc2NvcGU9c2l0ZQ%3d%3d#AN=23966708&db=mdc>.
Ryan, L., Nadel, L., Keil, K., Putnam, K., Schnyer, D., Trouard, T., & Moscovitch, M. (2001). Hippocampal complex and retrieval of recent and very remote autobiographical memories: evidence from functional magnetic resonance imaging in neurologically intact people. Hippocampus, 11(6), 707-714, <http://eds.a.ebscohost.com.ezproxy-b.deakin.edu.au/eds/command/detail?sid=4407c6c0-17c0-4903-8f8b-d747f14e6ba0%40sessionmgr4005&vid=6&hid=4113>.
Silverstein, A., Silverstein, V., & Nunn, L. S. (2002). Chapter Three: HOW WE SMELL AND TASTE. In , Smelling & Tasting (p. 21). Lerner Publishing Group, <http://eds.a.ebscohost.com/eds/detail/detail?sid=920db994-5070-42b0-9e07-030eb0462983%40sessionmgr4005&vid=27&hid=4108&bdata=JnNpdGU9ZWRzLWxpdmUmc2NvcGU9c2l0ZQ%3d%3d#AN=9159171&db=hxh>.
(2013). Medscape News and Perspective . Retrieved 2016, <http://emedicine.medscape.com/article/835585-overview#a1>..