We tend to forget the bad and stick with the good. In extreme cases, there are people who erase traumatic memories from their head. Not a trace remains of them. Scientists found decades ago that the phenomenon is common among individuals of all cultures and latitudes, but the physiological brain mechanisms involved were unknown.
Up to now. A recent work by researchers at the University of Texas at Austin (UT) published in the Journal of Neuroscience provides clues to understanding the origins of this psychological defensive barrier. And it’s a surprise: it takes more effort for the brain to forget an unpleasant experience than to fix it.
The scanner doesn’t lie
The researchers used neuroimaging techniques to record patterns of brain activity. They showed a group of healthy adults pictures of faces and scenes, and asked them to make an effort to remember or forget those that were pointed out to them.
Instead of analyzing what was happening in the brain areas involved in the control of information and long-term memory – the prefrontal cortex and the hippocampus – they focused on the regions linked to perception, especially the visual cortex , and in the patterns of activity that correspond to the representations that memory makes of complex visual stimuli.
They observed that, as suspected, people have a certain capacity to decide what we forget, and that putting it in motion requires a moderate brain activity in areas related to the senses and perception, greater than that required to fix a memory. According to Tracy Wang, psychologist and main author of the study, “it is the intention to forget what increases brain activity, and when it reaches a certain threshold, we begin to forget that experience that affects us .”
The researchers also found that study subjects were more likely to forget scenes than faces; The latter usually provide us with much more emotional information, which confirms that feelings play a decisive role in the memory mechanisms of human beings.
A flexible capacity
This work affects something known: memory is dynamic. The brain builds a memory from experiences and sensations that does not remain frozen: neural circuits modify it in the light of new experiences, or eliminate it, in processes that usually take place when we sleep.
Jarrod Lewis-Peacock, one of the study’s authors, points out on the UT website that “now that we’ve discovered clues to how the brain works to weaken certain memories, we can use this knowledge to develop treatments that help people shed of memories that cause them a lot of psychological damage, so much so that they can make them sick ”.
