Scientists have turned ordinary mice into super-smellers by boosting the number of a certain type of cell in the animals’ brains.
An adult mouse’s brain harbours a large pool of stem cells in a region called the subventricular zone (SVZ). These stem cells multiply and develop into cells that migrate to the brain’s olfactory bulb, which processes information about odours. There the cells develop further into mature neurons.
By genetically engineering mice, Federico Calegari at the Technical University of Dresden, Germany, and his colleagues prompted the stem cells in the animals’ brains to divide faster than usual. This generated extra SVZ stem cells, which gave rise to olfactory bulb neurons. These young neurons successfully connected to the existing neuronal network — suggesting that the newcomers could contribute to brain function.
Mice with an extra helping of SVZ stem cells performed as well as control animals on relatively easy olfactory tests. But when challenged to discriminate between highly similar odours, the enhanced mice performed significantly better.