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Is having a sense of smell a question of experience? Indeed it is! Using your nose is not an innate ability, it is simply a question of training.
This has recently been demonstrated by Jane Plailly and Jean-Pierre Royet, researchers at the laboratoire Neurosciences Sensorielles Comportement Cognition (CNRS/Université Claude Bernard Lyon 1) and Chantal Delon-Martin, a researcher from the Institut des Neurosciences in Grenoble (Inserm/Université Joseph
Fourier).
They performed a cerebral imaging experiment involving professional perfumers and student perfumers.
They demonstrated, for the first time ever, that similar areas of the brain are activated during both the perception and the imagination of odours, and that this activation is a function of the level of experience.
This result proves that mental olfactory imaging occurs in the same way as visual or auditory mental imaging, by reactivating olfactory images within the brain, and that this capacity develops with experience.
This research was published on 8 March 2011 on the site of the journal Human Brain
Mapping.
Each and every one of us is able to visualize the apartment where they live and to virtually walk around, or to mentally hum a well-known
tune.
However, can we remember, in thought, the smell of toasted bread or that of a fig to the extent where we can smell this odour?
Olfactory mental imaging is a much more difficult exercise than visual or auditory mental imaging and the majority of people say they do not possess this
capability.
Perfumers, however, experts in fragrance who are accustomed to smelling who evaluate and create odours, claim to be able to smell an odour even in its absence.
What is really happening here?
To answer this question, the researchers used functional Magnetic Resonance Imaging (fMRI) to compare the spatial organisation of cerebral activation in students from ISIPCA, the perfumery school in Versailles, with that of professional perfumers, a rare population (whose number does not exceed 500 worldwide and 120 within France and Switzerland).
Whilst in a scanner, they were asked to mentally imagine the smell of fragrant substances (1) when their chemical names appeared on a
screen.
The results showed that mental olfactory imaging activates the primary olfactory cortex (the piriform cortex) of the experts from the two groups, an area of the brain usually stimulated during perception.
This proves that similar areas are activated during the perception and the imagination of smells.
Olfactory mental imaging proceeds in the same way as visual or auditory mental imaging, by reactivation of olfactory images via an internal cognitive process (it is our brains themselves which generate this sensation) and not in response to an
odour.
There is a second lesson to be learned here. Among perfumers, intensive olfactory training influences the activation level of the neural network involved in mental imaging of smells.
Astonishingly, the higher the level of expertise, the more the activity of the olfactory and mnemic areas (hippocampus) decreases.
Hence, when the brain is trained, the neuron level "communication" is much better, it is quicker and more effective and the message is more specific, so training leads to a reduction in the activation.
This result demonstrates that olfactory mental imaging develops with daily training, and not as a result of an innate faculty.
In this study, the perfumers were capable of imagining odours rapidly, or even instantaneously, whereas the students exhibited some difficulties and needed to concentrate their attention more.
By easily reactivating mnemic representations of smells, the perfumers can make easy mental comparisons of scents and combine them with the aim of creating new
fragrances.
These results demonstrate the extraordinary capacity of our brains to adapt to environmental demands and to reorganize themselves in response to
experience.
Source
Plailly J., Delon-Martin C., Royet J.P. (2011)
"Experience induces functional reorganisation in brain regions involved in odor imagery in perfumers"
Human Brain Mapping, in press
http://www.inserm.fr/
(MDN)
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