Light switches memories on and off

Researchers use optogenetics to provide the first hard evidence that long-term potentiation at brain synapses is crucial for memory formation.

A team of researchers from the University of California, San Diego has determined the cellular mechanism of memory formation, putting an end to decades of speculation about the matter.

Most neuroscientists agree that memory formation involves the strengthening of synapses in the brain, and have assumed that this strengthening occurs by a form of synaptic plasticity called long-term potentiation (LTP), even though there was no hard evidence that this is the case.

more…

“The researchers created a genetically engineered virus carrying the Channelrhodopsin gene and injected it into the brains of rats, targeting part of the amygdala (commonly known as the brain’s “fear centre”) containing cells that process sound information. They then taught the animals to fear a sound, using the famous classical conditioning method …

Crucially, the researchers also found that a different pattern of light pulses delivered to the same cells could abolish LTP by inducing an opposing mechanism called long-term depression in the same synapses. This made the animals “forget” the association between the light pulses and electric shocks, so that they were no longer scared of the pulses, but this “erasure” was reversible – if the first pattern of pulses was delivered a second time, it induced LTP once again and reactivated the memory.

“We were playing with memory like a yo-yo,” Malinow told Nature news reporter Ewen Callaway, adding that it was “a bit of relief” that such challenging experiments worked, and that he and his colleagues can now “celebrate a little”

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Startling, and interesting.

On reading some science fiction at about the same time that CN posted this thread I got to wondering if it might be possible for a drug to erase all long-term memory – either immediately or using the principle that remembering something erases the memory straight after readout. I’ve noticed a tendency of anti-psychotic drugs to erase disturbing memories in the process of readout.