Stress Hormones Shift Brain to Random Behavior Patterns

Stress Hormones Shift Brain to Random Behavior Patterns

Stress hormones shift the brain to random behavior patterns. Usually the brain uses strategic behavior patterns that rely on past experiences to predict future outcomes, but scientists working with rats were able to induce random brain function or strategic brain function by manipulating the anterior cingulate cortex with a stress hormone.

Generally, humans synthesize past experiences in order to make better choices about the world around them. People spend time learning from their environments and from one another in order to process large amounts of information logically and optimize their interactions with their surroundings. In other words, people get what they want through planning and acting with purpose based on knowledge, but are there times when that is not the best strategy?

The brain also has the ability to employ random patterns of thinking and behaving. When people are presented with new or confusing situations, better outcomes may be achieved with unplanned, creative exploration. For example, unpredictability can help people with a tough challenge or unfamiliar environment. It can be useful to disassociate from past experiences rather than apply a model developed in a different setting. Scientists have wondered if the brain can tune out the influence of the past in order to see the world in a new light.

Alla Karpova and Gowan Tervo of the Howard Hughes Medical Institute’s Janelia Research Campus have explored how the brain can disconnect past experience from the decision-making process and instead employ randomness as a strategy. They met with resistance from fellow scientists, “They argue that it’s inefficient, and that it would be at odds with what some people call one of the most central operating principles of the brain – to use our past experience and knowledge to optimize behavioral choices,” said Karpova. The team forged ahead anyway.

They first triggered a random behavioral pattern in rats by creating a game in which rats searched for rewards against a computer-simulated competitor. When the competitor played weakly the rats employed strategy to win the treats. When the competitor became unbeatable the rats gave up all pretense of planning and fell back on random behavior. No matter what the rats did, what they expected to happen did not happen and so they stopped making choices based on expectations. When attempting to control their environment did not work, the rats stopped using past knowledge to beat the competitor and made random decisions.

However, the rats’ brains often got stuck in this random mode. After the game ended, or a weaker competitor was introduced, rats could not stop relying on random thinking. The scientists were faced with the challenge of how to revert their brains back to normal. The scientists discovered they could trigger strategic thinking by suppressing the stress hormone norepinephrine in the anterior cingulate cortex. Furthermore, experimentation proved they could switch the rats’ brains between the two modes by manipulating the levels of norepinephrine. When the stress hormone was increased the rats used random behavior patterns. When the stress hormone was decreased the rats returned to strategic behavior patterns, which are generally more useful and successful.

What implication does the study have for humans? Karpova noticed that the random behaviors in rats correlated with those of a condition known as learned helplessness. People with learned helplessness have impaired strategic-decision making abilities due to a situation in which they found themselves unable to control their environment. Could reducing stress hormones in the brain help people regain strategic behavior function?

Brief bouts of random behavior have benefits for people. Utilizing a variety of thinking and behavior strategies probably assisted humans’ evolutionary progress. However, strategic behavior patterns will most often help people achieve successful outcomes. Knowing that stress hormones can shift the brain to random behavior patterns, and decrease of the stress hormone can bring the brain back, may have applications for people suffering from some mental illnesses.

By: Rebecca Savastio


Medical XPress







One Response to "Stress Hormones Shift Brain to Random Behavior Patterns"

  1. Gary Gregorson   October 9, 2014 at 11:12 am

    Great article. It’s important to understand the effect stress and hormones have on each other. Check out this blog about hormonal changes in pro athletes and their wives, it’s really good stuff:

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