UNITED STATES (OBSERVATORY NEWS) — Scientists have found that people who lack olfactory bulbs can also smell. Possibly, alternative centers of smell are formed in their brain. The results of the study are published in the journal Neuron.
The ability to perceive odors depends on how well the olfactory information transmission system works – from sensory neurons in the nose through the olfactory nerves to the olfactory bulbs in the brain. Activation of small nerve structures inside the olfactory bulbs, called glomeruli, causes a sense of smell.
Until recently, it was believed that people who, due to a congenital pathology, lack olfactory bulbs, suffer from anosmia – they cannot smell.
Scientists led by Noam Sobel of the Weizmann Institute in Israel have found that people without olfactory bulbs can, however, detect and identify the same odors as the rest.
Researchers first came across two women who could smell, despite the lack of olfactory bulbs, during a review of the results of MRI in volunteers who took an odor perception test.
After that, scientists conducted an analysis of 1113 MRI scans published as part of the Human Connect project to create a “network map” of anatomical and functional connections in a healthy human brain, implemented by the US National Institute of Health since 2009. And they found three more young women who did not have clear olfactory bulbs, but they could smell. Not a single man deprived of olfactory bulbs has been identified.
A detailed examination of the brain of these women, including conventional and diffuse MRI, three-dimensional visualization of ultra-high definition and voxel morphometry, did not reveal any differences from the brain of ordinary people, in addition to the lack of olfactory bulbs.
Three women agreed to undergo odor testing as part of a group that included 140 women of the same age with a normally developed olfactory system. Participants were asked to smell ten different flavors and then characterize their smell using a choice of eleven descriptive words.
One of the three subjects could not describe the smells, and the other two described them in almost the same terms as the participants from the control group – the intersection was 96 percent. Moreover, the descriptions of these two women completely coincided with each other.
Scientists believe that in the case when the olfactory bulbs are for one reason or another underdeveloped or absent, the brain includes adaptation mechanisms to create alternative centers of smell.
“These women were born without olfactory bulbs, but due to the extreme plasticity of the brain, the glomeruli responsible for smelling developed somewhere else in their brains,” Novel Sobel, the first author of the study, quoted the press release of Cell Press. the brain has significant potential for change with minimal functional impact, and this may be one of its manifestations.”
In the future, scientists plan to continue their research and hope to find a way to teach them to distinguish the smells of people with congenital anosmia.
This article is written and prepared by our foreign editors writing for OBSERVATORY NEWS from different countries around the world – material edited and published by OBSERVATORY staff in our newsroom.
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