London: American scientists have developed a new technique which they say could help erase painful memories of a person permanently, a breakthrough that may pave the way for new drugs for post-traumatic stress disorder.
In tests on mice, researchers at John Hopkins University in the US removed a particular protein from the region of the brain responsible for recalling fear and found that the rats
were then unable to recall fear associated with a loud sound.
According to the scientists, the findings have important implications for patients whose lives were blighted by the post-traumatic stress disorder (PTSD) -- a stress syndrome
associated with war, rape and other traumatic events.
"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," lead researcher Dr Richard Huganir was
quoted as saying by the Daily Mail.
"Our finding describing these molecular and cellular mechanisms involved in that process raises the possibility of manipulating those mechanisms with drugs to enhance behavioural therapy for such conditions as post-traumatic stress disorder."
Behavioural therapy has been shown to ease the depth of the emotional response to traumatic memories, but not in completely removing the memory itself, making relapse common.
For their study, the researchers focused on the nerve circuits in the mice`s amygdala, the part of the brain known to underly so-called fear conditioning in people and animals.
Using sound to cue fear in mice, they found that certain cells in the amygdala conducted more current after the mouse was exposed to a loud, sudden tone.
They found temporary increases in particular proteins, called the calcium-permeable AMPARs, within a few hours of fear conditioning that peaked at 24 hours and disappeared 48 hours later. These proteins are uniquely unstable and can be
removed from nerve cells.
Dr Huganir said: "The idea was to remove these proteins and weaken the connections in the brain created by the trauma, thereby erasing the memory itself."
In further experiments, they found that removal of these proteins depended on the chemical modification of the GluA1 protein.
Mice lacking this chemical modification of GluA1 recovered fear memories induced by loud tones, whereas litter mates did not recover the same fear memories.
Dr Huganir said the findings suggested that drugs designed to control and enhance the removal of calcium-permeable AMPARs may be used to improve memory erasure.
`This may sound like science fiction, the ability to selectively erase memories. 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," he said.