Positive Memories To Fight Depression
Remembering pleasant moments in our life makes us feel better. However, the role of positive memories may be more important than we imagine, as in addition to regulating emotions, they have a positive effect on depression caused by stress.
A group of researchers conducted an experiment on guinea pigs that showed how the artificial reactivation of stored positive memories can suppress the effects of stress depression. Let’s see in more detail what it is.
Artificially induced positive memories
The study that demonstrated the relationship between positive memories and depression, published in the journal Nature , was conducted by scientists from the RIKEN-MIT Center for Neural Circuit Genetics, in collaboration with the RIKEN Brain Science Institute in Japan and Massachusetts. Institute of Technology (MIT).
The research was conducted in the laboratory of Susumu Tonewaga, director of the RIKEN Brain Science Institute Susumu Tonegawa and the MIT professor, who in 1987 received the Nobel Prize for discovering the variety of antibodies. The study addresses the question of whether a positive memory may be capable of overwriting a negative one.
To find an answer, the researchers turned to genetic engineering. Specifically, they analyzed the memory cells of the brain gyrus, or dentate gyrus, of some guinea pigs as memories were being formed.
They are activated with the help of an optical fiber that emitted a blue light projected right where the memories were formed.
Then, the research team would activate the memory cells created during previous experiences.
To test the method, the male specimens were exposed to a positive experience (i.e. they were placed alongside a female specimen) to stimulate the formation of the memory of this event. Subsequently, they were exposed to a stressful experience that resulted in a depression-like state in them.
While the guinea pigs were depressed, a light pulse was used to stimulate the dentate gyrus of some of them, in order to reactivate the positive experience.
Storing positive memories is essential
To the surprise of the researchers, this experiment showed a strong improvement from depression in guinea pigs to which the technique in question was applied. Brain circuit mapping of this effect also revealed two other areas of the brain that cooperate with the dentate gyrus in activating positive memories: the nucleus accumbens and the basolateral amygdala.
To test whether this surgery causes permanent changes (i.e. even in the absence of light stimulation) in the brain circuitry, the researchers applied chronic light to the dentate gyrus for over 5 days. Apparently, the action guaranteed the prolonged reactivation of positive memories.
Guinea pigs who received this therapy have been shown to be resistant to the negative effects of stress-induced depression. This suggests that storing positive experiences in memory may be helpful in suppressing or overwriting the negative effects of stress on behavior; this brings us to a new way of conceptualizing mood management.
Although the interaction between positive and negative experiences and their corresponding memories are little known, these milestones open the door to new approaches to the therapy of mood disorders.
The authors argue that it is too early to conclude that positive memories in general can mitigate the effects of stress-induced depression. However, they represent an additional possibility for research and for the development of treatments aimed at combating this disorder.
