Stress can improve ordinary, unrelated memories, a team of neuroscientists discovered recently.
Their results could offer a pathway for addressing post-traumatic stress disorder (PTSD) and related afflictions.
Researchers at the Czech Republic's Academy of Sciences, the State University of New York (SUNY) Downstate Medical Center, and Rockefeller University conducted the study using laboratory rats.
"Our results show that stress can activate memory, even if that memory is unrelated to the stressful experience," explained Andre Fenton, the study's lead author.
A common feature of PTSD and various mood and anxiety disorders is the formation of negative associations from otherwise innocuous stimuli or the recall of negative memories stimulated by unrelated, neutral circumstances. What's less clear is how stress influences these phenomena.
In these experiments, rats learned to make distinctions between left and right in a T-shaped maze. One day later, the researchers induced stress in the rats through a commonly practiced technique-placing them in a bucket of water in which they had to swim.
Other rats were placed in shallow water, where swimming was not necessary. Subsequent to this procedure, the rats were again tasked with navigating the maze.
Their results showed that the rats who had undergone the stressful swim showed better memory for which way to turn in the T-maze than those placed in shallow water.
These results show that stress can reactivate unrelated memories, leading the authors to hypothesize that, in humans, traumatic stress might reactivate non-traumatic memories and link them to the traumatic memory, thereby facilitating the pathological effects seen in post-traumatic stress disorder and other conditions.
The results appeared in the journal PLoS Biology.