During sleep, bad memories become less clear, claim U.S. researchers.
A group of researchers at Northwestern University in Chicago developed a technique that makes it possible to change human memories during sleep. The study was published in the journal Nature News.
Previously, many experiments on animals and observations of psychologists helped establish that the memory changes the focus from short-term to long-term during sleep, in other words, a consolidation of memory takes place. It was believed that the impact on it at this point may weaken or completely erase it.
The experiment involved 15 volunteers. All of them during the deep sleep phase were given to smell a scent that had previously been associated with a gentle electric shock. The results confirmed the assumption of researchers that during sleep the memories of unpleasant experiences become less clear.
To understand how strong the association between smell and electric shock is, the researchers used two independent methods. First, they watched how much sweat is released in the participants and it turned out that those who were subconsciously waiting for impact were sweating more. Second, the response of the brain to the smell was detected by a magnetic resonance imaging device. Both tests indicated that the memories became weaker.
It should be noted that the relation of stimuli (including smells) to bad memories is an important component of post-traumatic stress disorder (PTSD). The development of methods to reduce these abnormal connections, which both physicians and scientists are involved in, is associated with the expansion of knowledge about memory consolidation.
Another important study in this area was recently made and became the first step towards the creation of techniques to manipulate human memory. The researchers were able to implant artificial memories in experimental mice. According to the researchers, these experiments will help develop technology that will allow to erase bad memories and replace them with a positive experience from reality or created by artificial means. Moreover, it will be even easier to achieve it in humans than in mice, since the capacity for imaginative thinking and creativity will easily induce artificial images that are suitable for the replacement of these memories.