The olfactory bulb is an important structure in the olfactory system which is the system devoted to the smell and its lacking in any human leads to being unable to smell, a.k.a. anosmia.
At least, it was thought so.
The journal Neuron released a new study on November 6, and in the study, researchers claim that they have discovered a group of people who have the ability to smell even if they don't have the "olfactory bulb."
Actually, the back story of this discovery is a little surprising. In Israel, some researchers working on a study that was about imaging the brains of patients with a normal sense of smell by using MRI(magnetic resonance imaging).
Even though the ad they published for their study said that participants should have a good sense of smell, a woman who should be unable to smell according to her brain scan participated in the study. The researchers first thought maybe she didn't read that part of the ad, but when they asked about this to her, she said she could smell.
Researchers decided to do another study with subjects with left-handed women, just as the original subject and they discovered another woman without olfactory bulb, yet she was able to smell either.
The researchers created an "olfactory perceptual fingerprint" and with these 2 women and other 140 women who are about a similar age, they made a test and they asked these women how similar different smells, such as roses, banana, and strawberries. The answers of these 2 women were similar to the others', but their "olfactory perceptual fingerprints" were closer to each other than the others. However, they both couldn't smell roselike odors.
It's not exactly known how these two women can smell, but the researchers now are working on another study that involves people without the olfactory bulb and they test those people's ability to smell.