Mice aren’t what you would naturally think of when you’re told to imagine a ruthless killer.
Yet at the flick of a switch, scientists from Yale University School of Medicine have been able to transform a cute little mouse into a heartless murderer.
By using light to activate certain neurons in the brain the mouse would immediately jump on the nearest object, pin it down and repeatedly bite it.
This rather worrisome effect was manufactured after scientists worked out how to activate the mouse’s ‘predatory instinct’ inside its amygdala.
“When a non-edible item was placed in the cage, laser activation caused the otherwise indifferent mice to immediately assume a ‘capture-like’ body posture and seize the object, which was then held with the forepaws and bitten.”
“Behavior was interrupted immediately upon laser deactivation” explains the paper.
Testing out this ‘switch’, the team found that the mouse would target anything smaller than itself and would attack anything whether it was alive, dead or an inanimate object.
The only thing the mouse wouldn’t attack was one of its own kind.
What’s potentially even more disturbing is the accuracy with which the team were able to control their subjects.
By only activating ‘hunt’ part of the amygdala they found they could command the mouse to chase down its prey but only wound it.
Yet when they activate the ‘biting’ region they discovered the mouse would raise its hands and engage in fictitious eating, almost as though it were imagining food in its grasp.
What’s interesting is that their ability to control the mouse greatly depended on how hungry it was. So when it was very hungry its aggression would be heightened and it’s ability to act as command was increased.
Yet when the mouse was full its reactions would be dulled.
This suggests that for mice and for humans as well, the ability to engage this predatory part of our brains is very closely linked to how hungry we’re feeling.
Thankfully for us humans this predatory instinct usually only stretches as far as grumpily trying to find a McDonalds, not actually jumping on things and biting them.
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