(Medical Xpress) — Research from Karolinska Institutet shows that the human olfactory bulb – a structure in the brain that processes sensory input from the nose – differs from that of other mammals in that no new neurons are formed in this area after birth. The discovery, which is published in the scientific journal Neuron, is based on the age-determination of the cells using the carbon-14 method, and might explain why the human sense of smell is normally much worse than that of other animals.