By manipulating neural circuits in the brain of mice, scientists have found that memories and experiences - stored in two different parts of the brain - can be altered in a way that a negative memory can transform into a positive one.
The research reveals that the connections between the part of the brain that stores contextual information about an experience and the part of the brain that stores the emotional memory of that experience are malleable.
Altering those connections can transform a negative memory into a positive one, said researchers from Massachusetts Institute of Technology (MIT).
"There is some evidence from psychotherapy that positive memory can suppress memories of negative experience," said Susumu Tonegawa from Howard Hughes Medical Institute at MIT.
For example, recalling a favourite vacation may summon pleasure for years to come, whereas the fear that accompanies a memory of assault might cause a victim to never return to the scene of the crime.
According to Tonegawa, the contextual information about these events - where and when they happened - is recorded in the brain's hippocampus, whereas the emotional component of the memory is stored separately, in a region called the amygdala.
"The amygdala can store information with either a positive or negative valence and associate it with a memory," Tonegawa informed.
The findings suggest that neural circuits connecting the hippocampus and the amygdala might be targeted for the development of new drugs to treat mental illness.
The paper appeared in the journal Nature.