Tuesday, April 10, 2007

Olfactory Bulbs and Memories (republished)

Our ability to smell seems to come from somewhere primitive. Unlike the rest of the senses whose input seems to feed into the thalamus (part of the brain stem) our input for smell comes into the olfactory bulb which is tucked away beneath the temporal lobes.

Perhaps that is why a smell has such a powerful effect on our emotions. A certain smell can cause an inadvertant physical reaction (the smell of rotting meat for instance) and just adding a smell to a descriptive passage of prose adds immediate power. Yet it is easy to overdo and I often feel that there are not enough words for 'smell' - just perfume or odour.

Our ability to detect smell is quite extraordinary. It takes just one molecule to set off a signal, and just a slight change in the shape - just the mirror image of the molecule - can initiate an entirely different sensation. This makes the construction of artifical noses quite difficult. This was something I was involved in trying to produce during my post-doctoral work. The artificial nose has to be able to detect very low concentrations of gases and also be uniquely selective. In the project I was working on we used a sensitive electrical balance. My function as a chemist was to design coating that would adsorb (absorb just on the surface) the required molecule. The plan then was to construct an array of miniscule balances so that each smell would generate a fingerprint. It was very interesting work and sometimes I wish I was still doing it.

On the Athanasius Kircher site there is a feature about smells preserved from East Germany. That is something few of us ever think of doing - and yet the memory of a smell can sometimes transport us into our pasts more effectively than any other sense.

(This post has been repubished with 'comments allowed'. Comments seemed to be disabled before - I have no idea why becuse when I checked my settings - which I hadn't touched since my last post - they seemed to be still allowed. Ah well, they seem to be back now. Another little mystery, I guess).


Blogger Lee said...

Clare, it happens to me sometimes too. I find it's always a good idea to click on 'post options' in blue typeface underneath the body of the post before choosing 'save as draft' or 'publish'. For some reason the 'don't allow reader comments' option seems to tick itself from time to time.

This is a fascinating post on smell, which I thoroughly enjoyed reading.

Tue Apr 10, 08:24:00 am  
Anonymous Clare said...

Thanks for the tip, lee! This is the first time it's happened for me. Very starange.

Tue Apr 10, 09:17:00 am  
Blogger Jan said...

Smell probably most powerfully evocative of senses, I suppose...it immediately transports us elsewhere, to another time, place, emotion.
I wish some of them could be bottled..winds at Cape Cornwall, a brand new babe, eariest morning on a Thai beach...
Thanks Clare for interesting scientific explanations.

Tue Apr 10, 04:52:00 pm  

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