Drug-Free Method of Blocking Fear Memories
Behavioral Technique Can Reshape Fearful Memories
Dec. 8, 2009 -- Scientists at New York University report they have developed a drug-free, noninvasive way to temporarily block the return of fearful memories in people.
The technique, the researchers contend, could eventually change the way scientists view how the brain’s memory storage process works and perhaps even lead to new ways to treat anxiety disorders, including posttraumatic stress disorder.
Researcher Daniela Schiller, PhD, and colleagues at NYU say in a new study published in the journal Nature that they’ve been able to reshape memories. The process involves resurrecting unpleasant memories and creating a window of opportunity for reshaping the fears, a period called “reconsolidation.”
“Reconsolidation is a natural process that is likely occurring all the time,” Elizabeth Phelps, PhD, a professor of psychology at NYU, tells WebMD in an email. “Our studies suggest that simply retrieving a memory is enough to trigger the reconsolidation (i.e. re-storage) process. The trick is knowing enough about exactly how this process occurs to take advantage of it to restore fear memories as safe.”
Blocking Fear Memories
The researchers “trained” volunteers to be fearful of a visual stimulus, in this case colored squares, by pairing the images with mild electric shocks in a process called classical fear conditioning. Then they measured moisture on the skin of the volunteers, an indication of fear arousal.
After the fear memory was formed, some of the 65 participants were re-exposed to the image that produced the electric shock. This was followed by “extinction training,” in which they were exposed to colored squares but not shocked.
“The term extinction is generally used to describe new learning that the previously feared event is now safe,” Phelps tells WebMD.
The fear response disappeared only in people who went through extinction training. Those people who received extinction training after a six-hour window remained afraid of the squares, as did those in a control group.
Timing Is Critical
A year later in a follow-up experiment, 19 of the original participants received four shocks followed by presentations of the colored squares. This was meant to reinstate fears.