Brain scans of expert perfumers show an increase in size in brain regions associated with smell, compared to untrained individuals. The more experience a perfume professional has, the greater the increase, compared to his or her less experienced peers. Although such modifications of the brain have been seen with expertise in other realms, depending on other skills, these are the first results to show that expert olfactory training, too, can change the structure of the brain.
They say we grow wiser with age. If you’re a professional perfume maker, certain regions of your brain associated with odors are likely getting bigger, too. This is the conclusion of a team of French neuroscientists studying the connections between expertise and modifications of the brain. Although changes to brain anatomy and function have been seen in other experts, such as musicians, this study is only the second to look at olfaction. Probably, the authors suppose, because the sense of smell is less essential for our survival; compared to other mammals, it is sadly underdeveloped in humans; and because olfactory experts, like perfumers, are hard to come by.
Research performed earlier this year by members of the same group--Jean-Pierre Royet and Jane Plailly of the University of Lyon 1, and Chantal Delon-Martin of the Grenoble Institut des neurosciences, showed that experience working with scents alters the functioning of certain brain areas – specifically, those involved in odor imagery, or creating a mental image of an odor.
Other studies have shown that in patients suffering from olfactory problems (such as anosmia, the inability to perceive odor), atrophy of the brain’s gray matter was seen in regions associated with the sense of smell. Could the opposite be true? If one is an expert of olfaction, a specialist of smells, is the volume of these regions enhanced?
The group hypothesized that, yes, the volume of gray matter would be increased, both in regions associated with olfaction and with memory. To test this, they performed structural magnetic resonance imaging (MRI) scans on 48 subjects: 14 well-known perfumers, 13 students attending a major school of perfumery and 21 control subjects. The researchers examined whether the volume of these brain regions differed overall between experts and controls, and also whether a difference could be seen between younger and older experts.
Their results showed that, compared to individuals who had never received olfactory training, the professionals had larger volumes of gray matter starting at the gyrus rectus and extending to the medial orbital gyrus (GR/MOG). This area forms the border of one odor processing region, the olfactory sulcus, and lies next to a hypothesized second. Within the expert group, the volume of this region also increased in parallel with years of practice, revealing the effect of experience over time. Interestingly, in control subjects, the same brain area shrunk with age, suggesting that the perfumers’ expertise counteracted the effects of aging.
Two other brain regions were also larger among the perfumers, which corresponds to the function of these areas: the anterior cingulate gyrus, believed to be important in tasks requiring cognitive control when faced with emotional stimuli, and the caudate nucleus, which is involved in learning and memory.
Just how this happens – how the brain can selectively increase its volume in response to experience – is still not clear. Two possibilities are that additional neurons are recruited to the region being used so heavily, and that the activity of the neurons present becomes synchronized, resulting in a remodeling of the region’s structure. Adult neurogenesis, the production of new neurons in the adult brain, also remains a possibility.