Most of the times we like to make informed decisions we take into account our knowledge and the experience we have had in the past. But, in some situations it is better to explore a new situation that is unfettered by the past. A new study by the scientists at the Howard Hughes Medical Institute's Janelia Research Campus reveals that our brain can temporarily disconnect information about past experiences from decision making circuits which can trigger random behavior.
The research led by Janelia lab head Alla Karpova and postdoctoral fellow Gowan Tervo, was published in the September 25, 2012, issue of the journal Cell. In the study, it was observed that rats playing a game for a food reward usually acted strategically. However, when faced with an unpredictable and hard to beat competitor, they switched to random behavior. The animals sometimes got stuck in a random behavior mode; however they found that by manipulating the activity in a certain region of the brain, normal behavior could be restored in them. The random behavior is similar to the behavior shown by patients suffering from a psychological condition known as learned helplessness. The findings of this study may help explain that condition and suggest strategies for treating it.
Our brains integrate information from the past to guide decision making in new situations. However, under certain circumstances like if an animal wants to avoid a predator he can move unpredictable which increases its chances of survival, is more preferable. Karpova remarked that scientists have long speculated that the brain may a way of switching off the influence of past experiences so that behavior can proceed randomly. However, other disagrees as they think that it is inefficient, and it would be a hindrance to a person's ability to utilize his past experience to optimize behavioral choices.
Karpova and her colleagues experimented to find out if animals could be forced to switch into this random mode of behavior. They did this by placing rats in a very competitive setting in which a computer-simulated competitor determined which of two holes in a wall would provide a sugary reward. The virtual competitor, whose sophistication was controlled by the experimenters, analyzed the rats’ behavior to predict their future choices. The researchers found that when the normal animals realized that they could not outcompete them, they behaved randomly. The experiment gave them the evidence that the brain could generate both strategic and random behavior, Karpova and her colleagues experimented further to know how it switched between modes. The scientists speculated that it might involve region of the brain called the anterior cingulate cortex, where that internal model is likely encoded. It was finally observed that the animals could be manipulated to switch between random and strategic behavior by changing the level of a stress hormone called norepinephrine in the anterior cingulate cortex. When norepinephrine in the region was increased, random behavior was activated and when the same was suppressed, the strategic mode was enabled.
The team of researchers also observed that when subjected to competitive environment for a long while, the animal often continues to behave randomly even though such a behavior is no longer advantageous. The researcher drew parallels between this behavior and the condition of learned helplessness, in which strategic decision-making is hindered following an experience in which a person is unable to control the environment.
The scientists found that they could release the animals from this stuck state by lowering the release of norepinephrine in the anterior cingulate cortex. So, just manipulating a single neuromodulatory input into one brain area, the strategic mode could be dramatically enhanced. Karpova said that this discovery might shed light on what goes wrong in conditions such as learned helplessness and how it can be alleviated.