Victoria Gill, Science correspondent and

Kate Stephens, Senior science journalist

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The research has raised questions about what it means to alter the way laboratory animals think and feel

Neuroscientists in the US have successfully adapted mice to have functioning human cells inside their own brains.

The researchers hope that potential treatments for psychiatric and neurodevelopmental diseases that only occur in humans could now be tested on the laboratory rodents.

While mice with brains that are partly human might sound like a Kafkaesque experiment, the scientists said these are not "mice that think like humans".

The animals are genetically engineered - and surgically altered - so that some of their brain tissue is human.

S Pasca/Stanford

In scans of the implanted mice, researchers were able to see connections between the human brain cells and the rest of the mouse brain

The aim of this ethically complicated breakthrough was to better understand the biology of brain disorders for which…