Brain acts randomly when 'caught in a spot'

A new research has demonstrated that brain performs random actions when it temporarily disconnects the information about past experience from decision-making circuits.

The study conducted at Howard Hughes Medical Institute studied rats where rats played a game for a food reward usually acted strategically, but switched to random behavior when they confronted a particularly unpredictable and hard-to-beat competitor. The animals sometimes got stuck in a random-behavior mode, but the researchers found that they could restore normal behavior by manipulating activity in a specific region of the brain.

"We thought if we came up with very sophisticated competitors, then the animals would eventually be unable to figure out how to outcompete them, and be forced to either give up or switch into this [random] mode, if such a mode exists," Karpova says. And that's exactly what happened: When faced with a weak competitor, the animals made strategic choices based on the outcomes of previous trials.

But when a sophisticated competitor made strong predictions, the rats ignored past experience and made random selections in search of a reward.

Alla Karpova's team observed that animals in their experiments sometimes continued to behave randomly, even when such behavior was no longer advantageous.

The study is published in the journal Cell.