Scimex: Recalling positive memories seems to alleviate depression-like behaviours in mice, according to new research by US scientists. The study shows specifically that it is the memories associated with positive events, rather than the positive event itself, that triggers the antidepressant effect. However the authors caution that although the findings may have therapeutic implications, it is currently unclear how they may translate into humans.
Recalling positive memories seems to alleviate depression-like behaviours in mice, reports a paper in this week's Nature.
The study shows that it is activation of the memory trace associated
with a positive event, rather than the positive event itself, that
triggers the antidepressant effect. Although the findings may have
therapeutic implications, it is currently unclear how they may translate
Susumu Tonegawa and colleagues identified the specific neural engram (in
which memory traces are stored) created when male mice were exposed to
female mice, a positive experience, and tagged these neuronal cells so
that they could be reactivated with pulses of light. Mice were then
subjected to stressful conditions that induced depression-like
behaviour. Artificial reactivation of the positive memory traces
instantaneously suppressed depression-like behaviour. The authors also
showed that repeated reactivation of the positive memory seems to
increase resilience to stress-induced depression-like behaviour even
after the reactivation had finished, whereas exposure to a positive
experience did not.
The positive memory traces reactivated in this study are located in a
region of the brain called the hippocampus, which is thought to have a
role in regulating stress responses, although the precise mechanisms
involved in this process are unknown.