Scientists say they have discovered a biological anomaly that can change the way we understand our sense of smell.
A study in the journal Neuron shows that some people can smell normal, although they lack the part of the brain that is considered crucial for the smell ̵
Missing bulbs should cause anosmia (cannot smell).
It is curious that the phenomenon affects mostly left women and has never been detected in men.
How does smell work?
And how to smell a fresh cup of coffee, a garden flower or even a tattered baby diaper?
The present science says that odors enter the nose, where nerve endings are excited.
This creates an electrical signal that travels to a specialized part of the brain called olfactory bulbs.
They process the signals coming from the nose to determine what we smell.
With the exception of researchers at the Weizmann Institute of Science in Israel, they have found people who have normal sense of smell, although without bulbs.
How often is this?
Scientists came across the first example when they scanned the brains of people with healthy sense of smell as part of a completely unrelated study.
Researcher Professor Noam Sobel told BBC News: "We couldn't find any sign of an olfactory bulb in her brain, this is an anomaly – it doesn't make sense, right?"
The woman was left and researchers wanted to compare the brain with other left women to see what's going on.
They only had to scan nine more brains before finding another bulbless woman. , but cracking sense of smell.
"It was incredibly shocking. That started ringing on all the bells," said Professor Sobel.
The team then turned to a public library of 1,113 brain scans – the Human Connectome Project – and found more examples.
The phenomenon is never detected in men, but is present in more than 4% of left-handed women.
Prof. Sobel said there was "absolutely no idea" why gender and left-handedness appear to be involved.
And what's going on?
There are a number of ideas, but only more research will show what is right.
One possibility is for women to have olfactory bulbs, but they are so small that they cannot be detected on a brain scan.
However, this does not explain how they retain such good sense of smell with such compromised bulbs.
Another explanation is the ability of the brain to adapt, known as plasticity.
If a child is born without olfactory bulbs. , then maybe another part of the brain takes responsibility for the aroma of the bulb.
But researchers have come up with a more controversial explanation that challenges the current understanding of smell.
They argue that bulbs may not participate in odor recognition and instead play a different role, potentially in localizing the odor rather than identifying it.
"This is a dramatic alternative," Prof Sobel said.
He added: "My premonition is that olfactory bulbs may be more important to where."
What do the experts think?
"The fact that their olfactory capacity is almost identical to that of normal individuals is very surprising," Prof. Matthew Cobb of Manchester University told the BBC.
Prof. Cobb, author of the forthcoming book A very short introduction states that the living brain is very flexible and can compensate for the lack of olfactory bulbs. intellectual functions – is compressed into a small triple of cells, but still it is with
"In China, a young woman does not have a brain – the structure at the heart of the brain involved in coordination – and although there is unclear speech and poor coordination, these symptoms are nowhere near as serious, as much as animal research suggests they should be. "
Follow James on Twitter .