Researchers Puzzled by a Group of People Missing a Brain Structure to Smell but Are Still Sniffing Odors Comfortably

It's widely known that our senses are directly connected to different centers in our brain. However, experts were baffled to find out a 29-year-old woman's ability to sniff odors better than average people, despite her brain missing an important structure, according to a new study published in the journal Neuron. The woman is not the only one to possess the fascinating ability but there are more like her who defy logic provided by medical science.

This small group of people underwent brain scans and it was revealed that they did not have olfactory bulbs. Olfactory bulbs in the brain help to process information like smells from the nose. The group of researchers led by Noam Sobel, a professor of neurobiology at the Weizmann Institute of Science in Israel, discovered by chance while conducting a different study on human brains using MRI scans. The experts had put out an ad for participants who had a good sense of smell and some of the brain scans showed the absence of the olfactory bulbs, suggesting that it would have prevented the woman from distinguishing different smells.

When they asked her, the woman claimed that she had a very good sense of smell. Sobel and his team conducted more scans and tests on her and found that her sense of smell was slightly heightened than an average person. "Our understanding is that odors are essentially mapped on the surface of the bulbs and the brain somehow reads this map," Sobel told Live Science. "If you lack this map, you should also lack the ability to smell." Then the team searched through a database called Human Connectome Project which had published over 1,100 MRI scans along with information about the volunteers' sense of smell. 

Of all those volunteers, 606 were women and three had no olfactory bulb. One of those three women was left-handed too. Similar tests were also conducted on rodents back in the 80s and 90s that revealed how the rodents were able to smell even after their olfactory bulbs were removed. Back to the study conducted on humans, there was no clear explanation behind only women having this mysterious ability, specifically left-handed women. "Most brain-scan studies exclude left-handed participants to reduce variation among participants, which could be a reason why this wasn't found before," Sobel said. "That's because people who are right-handed can have their brains wired differently than those who are left-handed." 

Sobel suggested some hypotheses. His first estimation suggested that those women were born without olfactory bulbs but as their brain developed in infancy, it gained the ability to detect smells. It could have been that a separate region of the brain had taken up the task of transmitting scent information to the brain. "The sort of more exciting alternative might be that you don't need olfactory bulbs to detect, discriminate and identify smells," Sobel theorized. Thomas Cleland, an associate chair and professor in the department of psychology at Cornell University who was not part of the study, remarked how it was unlikely that the nerves that make up the olfactory bulbs were missing in those patients. 

"It’s more likely that the relevant circuitry, or something resembling it, is somehow misplaced, internally anatomically disorganized, and/or differently shaped, as opposed to being genuinely absent," Cleland told Live Science in an email. "And if this is true, it’s not that strange that these women can smell somewhat normally." "The idea that maybe there's a different structure that's taking over the role of the olfactory bulb would be surprising and amazing," Joel Mainland, an associate member of the Monell Chemical Senses Center in Philadelphia, who was also not a part of the study, told the outlet.