US scientists have transferred the sense of smell from rats into the brains of purpose-bred mice, in a world first.
In the study, at the University of Colombia, New York, the researchers first genetically silenced, or killed, neurons that mice use to be able to smell and found that these mice could then not find cookies hidden in their cages.
Next the scientists transplanted rat stem cells into mouse embryo brains with those ‘smelling’ genes deactivated and saw that the rat cells replaced the silenced cells.
Once they were born, those mice, with hybrid brains, were able to sniff out the cookies in their cage by using the transplanted rat neurons.
It is the first time that an animal has been able to use the sensory apparatus of another to sense and respond accurately to the world, and this is one indication of how flexible the brain may be in integrating external brain cells.
Kristin Baldwin, the lead researcher from Columbia, said: “Right now, researchers are transplanting stem cells and neurons into people with Parkinson's and epilepsy. But we do not really understand how well that will work.
“With hybrid brain models, we can start to get some answers and at a faster pace than a clinical trial.”