Saturday, 7 January 2012

OLFACTION SATISFACTION

Take time to stop and smell the roses.


Why?


Our sense of smell has the ability to stir in us great emotion. Happy childhood memories, repulsion, fear or a sense of De' ja vu'.

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HOW DOES OUR SENSE OF SMELL WORK?

At the top of your nose inside there is a section of epithelium containing special neurons. These neuron contain cilia which are little hair like projections (the same type we damage in our lungs through smoking) to help make the area of air that they come into contact with greater.

These neurons come into contact with molecules in the air from a particular object and this is what we smell. In order for us to smell something it needs to be able to give up these molecules. The molecule binds to the cilia and triggers a reaction which is processed by the brain and enables us to perceive and interpret the smell.

In the book Molecular Biology of the Cell:
Humans can distinguish more than 10,000 different smells (odorants), which are detected by specialized olfactory receptor neurons lining the nose.... It is thought that there are hundreds of different olfactory receptors, each encoded by a different gene and each recognizing different odorants.


SO WE KNOW HOW SMELL WORKS, BUT HOW DOES IT TRIGGER SUCH STRONG MEMORIES? 


Smell is believed to be such an emotive trigger as the olfactory cortex (part of brain determining smell) has a direct neural link to the hippocampus. Yes this is spelt correctly. The hippocampus is part of the limbic system which help us to form our short and long term memories.


It is this direct link and processing which makes it so sentimentally arousing. Other senses are processed in the thalamus and then make their way to the limbic system. You see! 


Now we all love Dr Karl Kruszelnicki, he makes being a geek ├╝ber cool. He explains on ABC's scenic news that this type of memory is called a "Proustian Memory". It's named after Marcel Proust, one of the greatest novelists of the 20th century. He describes this phenomenon in the opening chapter of his novel Swan's Way, the first novel in his mammoth seven-part work, Remembrance Of Things Past.


Primitively speaking this may have happened  for several reasons. So pre-refrigeration we could smell if our woolly mammoth meat was rotten; to detect food; to attract a mate and for our babies to make their way to the mothers breast whilst they were out beating the path to civilisation.


WHAT CAN YOU SMELL THAT TRIGGERS A MEMORY?


I have had many an occasion where de' ja vu' has kicked in just through a sense of smell. I can't explain it more than that.


Last night though I had the pleasure (for once) of taking the dog for a walk, whilst my husband did the dishes (also for once).
As I walked the familiar, yet unfamiliar streets as it had been such a while since I had the privilege (wow so many people are renovating, I am green with envy!), I strolled past houses and BANG there it was....a smell.


Not good, not bad, just a memory.


One of them was the smell of an older couples home and it brought me back to Nan and Pa Crafters home on Tollner Road. Not my real grandparents, but a lovely old couple we lived next door to when I was very young, 4 and under.


It is the smell of tea leaves, tobacco and old fashioned soaps, mixed with lemon scented washing up liquid. It may not sound ideal, but it was a lovely smell and made me remember some lovely people.


Another smell from my childhood is one I am experiencing now, summer rain and the smell of a thunderstorm. Today is a sultry 32c and it rained late this afternoon. My husband mowed the lawns this morning and the orange and lemon trees are in summer bloom. The mixture of scents is one so rich and warming and reminds me of how summer was always a happy time as we were all outdoors, playing, exploring, mixing with the neighbourhood.


This was a 39c day in Clare and a summer storm rolled in over the vineyard, normally you would see the Skilly Hills Ridgeline behind the trees
All roads lead to....PINE TREES surrounding Mount Gambier.




It brings me to another memory triggered by smell. At work the other day we were talking about Christmas trees and one colleague had been to the Christmas tree farm to get a real tree. Everyone oohed and aahhed. I stayed silent. Repulsed by the thought of a pinus radiata in my home. Why? We grew up in the South East of South Australia, surrounded by them. The bane of my allergies and asthma as a child, but excitement in winter with all the mud puddles bathed in yellow rings of pine tree pollen.



Isn't it amazing what a smell and memory can do?


I am grateful that I can smell, for a while after a home cleaning - over bleaching in an unventilated room incident, I lost my sense of smell. There are also many medical reasons why people can't smell. We all know the feeling of a blocked nose in winter with a cold and how we can't smell anything and taste does not seem the same either.


Be grateful for your sense of smell and take time to stop and smell the roses!








http://www.abc.net.au/science/articles
http://scienceblogs.com/cortex/2009/11/smell_and_memory.php

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