Apparently, according to research done at the Weizmann
Institute (in Israel), how we rate a certain smells (i.e. whether they are pleasant
or not) has to do with an organizing principle for the way we smell. At a
deeper level, certain nerves respond to particular scents and it is this
connection that allowed researchers to tell whether their test subject found a smell
pleasant or unpleasant.
This kind of organisation is seen in other sensory organs.
For example, in the eye, the receptors are arranged to map out visual
coordinates. The inner ear, as well, is set up based on tonal scale. But until
now, the organizational principle for a sense of smell has remained a
mystery.
As scientists began delving into this conundrum, they began
noticing that there was a connection between the chemical structure of an odour
molecule and its place on the ‘pleasantness scale’. Professor Noam Sobel
figured that maybe the smell receptors in the nose were arranged on the nasal
membrane according to this scale. Note that this idea goes against what was thought
previously, which was that the various receptors were mixed, distributed evenly,
but randomly on the membrane.
Using lots of tiny electrodes attached to many (presumably
very patient) volunteers’ noses, scientists found that the strength of response
from each nerve varied from place to place in reaction to different smells.
Further investigation showed that the intensity of any reaction was linked to
the odour’s place on the pleasantness scale. Therefore, their hypothesis seems
correct.
'We
uncovered a clear correlation between the pattern of nerve reaction to various
smells and the pleasantness of those smells. As in sight and hearing, the
receptors for our sense of smell are spatially organized in a way that reflects
the nature of the sensory experience,' says Sobel. This doesn’t mean that
individuals may experience smells differently, but instead suggests that
cultural context and personal experiences may cause a certain amount of
reorganization in smell perception over a person’s lifetime.
I
knew that my obsession with coriander leaf had something to do with having Indian
neighbours when growing up!
Credits:
Long Nose Fish Fine Art Print - Sara Raber
New Scientist
Science Daily
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