Monday, December 17, 2012Scientific publications

The special brain of perfumers


Areas (those linked to olfaction) that are more developed, and which enlarge with expertise … Researchers investigated the brains of professional perfumers and of student perfumers. They have found that the gray-matter of "noses" (the "nez", in French), the professionals who designed perfumes, is much different than the untrained people’s. Another proof of the incredible ability of our brains to adapt to the needs …

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CNRS Press release

The French Centre National de la Recherche Scientifique (CNRS; National Centre of Scientific Research) has released a communiqué. Brain areas linked to olfaction are more developed in professional perfumers than in the average person. Further, the longer their expertise, the more gray-matter there is in their olfactory areas.
This new example of the impressive plasticity of the human brain has been released by researchers from the CNRS and from the French INSERM (Institut National de la Santé et de Recherche médicale; National Institute on Health and for Medical Research), a team known as Codage et mémoire olfactive (Coding and olfactory memory), based in Lyon (France), in the Centre of Neurosciences (CNRS/Inserm/Université Claude Bernard Lyon 1/Université Jean Monnet Saint-Etienne).
These results, thanks to anatomical MRI performed on professional and student perfumers, and on untrained control persons, show that training counterbalance the diminishing volume of the gray matter in the olfactory areas when ageing, as seen as the public at large. This work is published in the 12 December issue of NeuroImage.

In previous works, these same researchers have demonstrated that, thanks to their training, perfumers get the ability to imagine a fragrance, and to "smell" it in their nose, though it is physically absent: an ability far beyond the reach of the average people.
The scientists have also reported that, the longer the perfumers' expertise, the lower the activity in the olfactory and memory areas. This result, paradoxical at first sight, is explained by the fact that the neuronal communication is more efficient, faster and more specific in these people.

Following these works, the researchers wondered whether the extensive training of perfumers could lead also to an increase of the volume of the gray matter in the brain areas linked to olfaction.
In order to answer this question, they performed an MRI on 14 renowned perfumers, comprising Jean-Claude Ellena and Daniel André. This same test was performed on 13 students of the Institut Supérieur International de la Parfumerie, de la Cosmétique et de l'Aromatique (ISIPCA;  post-graduate studies in Perfumery, Cosmetic and Aromas), in Versailles (Paris area), and 21 untrained volunteers, who had no specific olfactory expertise, whatsoever.

To be a "nose" is not innate

The MRI detected  the gray-matter volume in the primary olfactory (piriform) cortex (PC) and in an orbitofrontal area that surrounds the olfactory sulcus is larger in all perfumers than in untrained volunteers. This brain development may be due to an increase in the number of dendritic markings (the axons, or the long, slender projection of nerve cells, at the end of which the synapses allow for the communication between neurons, through emission/capture of neurotransmitters), or, maybe, to an increase in the number of neurons, a not yet demonstrated hypothesis…

Further, these works show that the gray-matter volume is directly correlated to the perfumers’ expertise. The more trained, the larger the volume of their olfactory areas.
On the other hand, the researchers have found that, in the untrained people, these brain areas noticeably diminish when ageing, a continuous and general phenomenon when no training is performed. Thus, the brain modifications seen in perfumers would be linked to their training, and not to innate peculiarities.

These results are somewhat similar to the structural modifications found in other experts, such as musicians, sportspersons, multilingual people, mathematicians, or taxi drivers. All these specialists reorganize and over-develop brain areas that are specific to their expertise. The fantastic ability of our brain to adapt to its environmental demand, and to reorganize, thanks to training, seems to be limitless.

Perfumers' expertise induces structural reorganization in olfactory brain regions . Chantal Delon-Martin, Jane Plailly, Pierre Fonlupt, Alexandra Veyrac and Jean-Pierre Royet. NeuroImage, 12 December 2012. (in French)
• Also see : the scientific article on the INSERM website

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