Memories are often associated with a particular emotion – you feel anxious on the street where you got assaulted, say. But those associations are malleable. Now, researchers have used a technique in which pulses of light switch brain cells on and off to change bad memories into good ones. First they gave male mice mild electric shocks and labelled the neurons that stored the memory. When those memory cells (pictured, red) were later re-activated with laser light from a fibre optic cable (black), the mice showed fear. However, when the neurons were stimulated as the mice were given a positive experience – female company – and then again re-activated by light pulses, the mice were no longer afraid. In fact, they enjoyed the feeling. It’s early days and the technique is extremely invasive, but the research could eventually bring better therapies for anxiety and post-traumatic stress disorder.
Written by Daniel Cossins
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