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As a memory forms, certain neurons are incorporated into a memory trace, a neural network associated with a particular experience that is active when the memory is recalled. By permanently altering those neurons in mice, researchers can control their activity. Neurons are engineered to produce channelrhodopsin (Chr), a light-sensitive ion channel, once they’re recruited into a specific memory trace. From memory formation onward, blue light can activate them, triggering the animal to act as if it is recalling the previous experience.
Over the past decade, researchers have developed and refined techniques to activate channelrhodopsin to make a mouse behave as if it’s recalling a specific experience (Nature, 484:381–85, 2012).
Scientists engineer mice such that neurons will produce channelrhodopsin once recruited into a memory trace. The mouse’s diet determines when the neurons are vulnerable to this effect.
As the mouse experiences a foot shock, delivered in a ...
