The findings are published online in the journal Neuropharmacology.

"These findings are very important in disorders like PTSD or drug addiction. One of the common problems associated with these disorders is the obtrusive recall of memories that are associated with the fearful, emotional experiences in PTSD patients. And people suffering with addiction are often exposed to environmental cues that remind them of the rewarding effects of the drug. This can lead to drug relapse, one of the major problems with persistent addictions to drugs such as opiates," explains Laviolette, an associate professor in the Departments of Anatomy and Cell Biology, and Psychiatry. "So what we've found is a common mechanism in the brain that can control recall of both aversive memories and memories associated with rewarding experience in the case of drug addiction."

In their experiments using a rat model, the neuroscientists discovered that stimulating a sub-type of dopamine receptor called the "D1" receptor in a specific area of the brain, could completely prevent the recall of both aversive and reward-related memories. "The precise mechanisms in the brain that control how these memories are recalled are poorly understood, and there are presently no effective treatments for patients suffering from obtrusive memories associated with either PTSD or addiction," says Lauzon. "If we are able to block the recall of those memories, then potentially we have a target for drugs to treat these disorders."

"In the movie, 'Eternal Sunshine of a Spotless Mind,' they attempted to permanently erase memories associated with emotional experiences," adds Laviolette. "The interesting thing about our findings is that we were able to prevent the spontaneous recall of these memories, but the memories were still intact. We weren't inducing any form of brain damage or actually affecting the integrity of the original memories."