Fake memory implanted in mice with a beam of light

Hazy recollection: I’m sure I buried some cheese here.

Paul.J.Hurtado

If you’ve ever been frustrated by erratic memories, spare a thought for the mice involved in a study published in the journal Science. Researchers have been able to consistently create a “false memory,” making a mouse fearful of a place it has no reason to fear. The memory was implanted by shining blue light into the mouse’s brain, which triggered a carefully chosen group of neurons.

The researchers used optogenetics, a technique that allows precise control of brain circuits. The control is achieved by expressing proteins that act as switches in particular types of brain cells. These switches are channels that, when struck by a particular color of light, allow charged particles into or out of the neurons, which will either activate or silence them.

Susumu Tonegawa of the Massachusetts Institute of Technology and his colleagues wanted to find out whether they could create a new, negative association by flipping the switch on an old, neutral memory while giving the mouse a negative experience. Would this lead the mouse to be scared of the old memory?