Neuroscientists wipe specific memories, permanently

Posted by Emma Woollacott

In Eternal Sunshine of the Spotless Mind, two people undergo a procedure to erase the memory of one another from their minds. And now love-lorn mice, at least, can experience the same relief from upsetting memories.

Researchers at the John Hopkins University School of Medicine say they have successfully wiped out traumatic memories in mice by removing a protein from the region of the brain responsible for recalling fear.

"This may sound like science fiction, the ability to selectively erase memories," says Dr Richard L Huganir, professor and director of neuroscience. "But this may one day be applicable for the treatment of debilitating fearful memories in people, such as post-traumatic stress syndrome associated with war, rape or other traumatic events."

The team studied the nerve circuits in the amygdala - which governs fear conditioning in people as well as animals - and found that certain cells in the amygdala conducted more current after the mouse was exposed to a loud, sudden tone.

Examining the proteins in the nerve cells of the amygdala before and after the unpleasant sound, they found a rise in the amount of particular proteins — the calcium-permeable AMPARs — which peaked 24 hours after the frightening sound and disappeared 48 hours later.

Because these particular proteins are uniquely unstable and can be removed from nerve cells, the scientists theorized that they might be able to permanently remove fear by eliminating them at the same time as carrying out behavior therapy. 

"The idea was to remove these proteins and weaken the connections in the brain created by the trauma, thereby erasing the memory itself," says Huganir.

And they found that it worked: chemically modifying the GluA1 protein stopped mice from recovering fear memories, while their unmodified littermates kept their memories intact.

Huganir says the findings show that it really could be possible to erase traumatic memories.

"When a traumatic event occurs, it creates a fearful memory that can last a lifetime and have a debilitating effect on a person’s life,"

he says. "Our finding describing these molecular and cellular mechanisms nvolved in that process raises the possibility of manipulating those mechanisms with drugs to enhance behavioral therapy for such conditions as post-traumatic stress disorder."

Other proteins have also been shown to be involved in memory storage and retrieval. Two years ago, neuroscientists at the Medical College of Georgia showed that artificially increasing levels of  α-CaMKII could displel painful memories.