In one experiment, rat neurons helped mice restore their senses of smell—the first time any animal has perceived the world through the sensory hardware of another species

In recent experiments, rat brain cells filled in for lost neurons in mouse brains, raising new possibilities for growing donor tissues across species.

Mice that had been genetically modified to lack the ability to smell could sniff out hidden cookies when sensory neurons from rats were grown in their brains

Scientists develop hybrid mice by filling in missing cells and structures in their brains with rat stem cells.

Researchers at Columbia University have engineered mice with part-rat, part-mouse brains that allow them to smell as rats do. This breakthrough demonstrates the brain's capacity to integrate foreign cells and could advance our understanding of and ability to treat human brain diseases.