Chronic stress can alter a rat’s brain, creating a creature of habit that makes mechanical, habitual decisions instead of switching up their behavior to earn rewards, a study discovered.
Chronic stress has been known to influence behavior and memory due to the discharge of hormones that affect the brain. However, to determine how it alters decision-making, Portuguese researchers carried out lab tests on groups of rats.
In one test, the rats were trained to push levers to gain rewards: food and sugar.
However, dissimilar from the regular, or control rats, the anxious rats repeatedly pressed the same lever even when it did not produce a reward.
When looking at the brains of rats that underwent 21 days of stress-inducing situations, the researchers discovered that two parts of the brain connected to decision-making, the prelimbic cortex and the dorsomedial striatum, had shrunken.
A third area of the brain needed for habit creation had grown in anxious rats. The switch to mechanical decision-making might be a managing mechanism to aid the animals in conserving energy.
However, it can be “highly detrimental” when hindering the capacity to become accustomed to altering environments, lead author Eduardo Dias-Ferreira of the University of Minho wrote.
“Such impairment might be of relevance to understand the high co-morbidity between stress-related disorders and addictive behavior or compulsivity,” he stated.
It also “has a broader impact spanning activities from everyday life decisions to economics.”
The study is available in the journal Science.
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