Scientists have uncovered a two-step process by which our brains can supposedly suppress emotional memories.
The finding, detailed in the July 13 issue of the journal Science, has implications for those suffering from emotional disorders such as depression.
In the study, 16 test subjects were asked to commit to memory 40 different pairs of pictures, consisting of a “neutral” human face and a disturbing picture such as a car crash or a wounded soldier.
After memorizing each pair, the subjects were placed in a functional MRI brain scanner. They were shown only the face images and asked to either think or not think about the disturbing image previously associated with it.
When actively trying to forget, the prefrontal cortex lit up, indicating it was active. In humans, the prefrontal cortex is involved in higher cognitive functions like orchestrating thoughts and actions. Specifically, two regions of the prefrontal cortex appeared to work in tandem to suppress the negative memory in a two-step process. First, the sensory aspects of the memory were blocked. Next, emotions associated with the memory, and then the memory itself, were suppressed.
“We have shown in this study that individuals have the ability to suppress specific memories at a particular moment in time through repeated practice,” said study Brendan Depue of the University of Colorado in Boulder.
The team suspects that the more traumatic an emotional memory is, the more practice is required to suppress it. “In cases like this, a person could need thousands of repetitions of training to suppress such memories,” Depue said. “We just don’t know yet.”