Short stress may enhance learning and memory

Acute stress – a short stressful incident – may enhance learning and memory through the effect of the stress hormone cortisol on the brain’s prefrontal cortex, revealed by researchers at the University at Buffalo.

Specifically, they demonstrated that acute stress increases transmission of the neurotransmitter glutamate and improves working memory, in trials using rodents as an animal model.

“Stress hormones have both protective and damaging effects on the body,” said Zhen Yan, professor of physiology and biophysics at UB and senior author on the study. “This paper and others we have in the pipeline explain why we need stress to perform better, but don’t want to be stressed out.”

The study published in the Proceedings of the National Academy of Sciences.

To test the effect of acute stress on working memory, Yan, Yuen and colleagues trained rats in a maze until they could complete it correctly 60-70 percent of the time. When the rodents reached this level of accuracy for two consecutive days, half were put through a 20-minute forced swim, which served as acute stress, and then were put through the maze again.

Results showed that the stressed rats made significantly fewer mistakes as they went through the maze both four hours after the stressful experience and one day post-stress, compared to the non-stressed rats.

The researchers also determined that the stressful experience did not increase depression or anxiety-related behavior in the animals.

“It is known that stress has both positive and negative actions in the brain, but the underlying mechanism is elusive,” said Yan. “Several key brain regions involved in cognition and emotions, including the prefrontal cortex, have been identified as the primary target of corticosteroid, the major stress hormone. “Our current study identifies a novel mechanism that underlies the impact of acute stress on working memory, a cognitive process depending on glutamate receptor-mediated excitatory signals in prefrontal cortex circuits.”

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All these studies should bring new insights into the complex actions of stress in different circumstances that may be applicable to humans in the future.

Source: University at Buffalo, USA

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