Researchers found that stress can lead us to choose higher-risk options when we are experiencing chronic stress. Luckily, they also found that the same process that causes this reaction could also be used in reverse to restore normal behavior.
The cost-benefit conflict refers to a situation that we often face in everyday situations wherein we are faced with two options which both have positive and negative facets. For instance, one may be faced to choose between a low-paying job that allows for more free time or a high-paying job that is more time-demanding.
Researchers from the Massachusetts Institute of Technology (MIT) found that stress largely influences decision-making in cost-benefit situations. As it turns out, when faced with chronic stress, there is a tendency to choose the high-risk, high-cost option.
Chocolate Milk Test
In a previous study, researchers trained rodents to go into a maze where they were faced with two options: highly concentrated chocolate milk with harsh bright lights, or less concentrated chocolate milk but with tolerable dimmer lights. When researchers inhibited the connection between cortical neurons and striosomes through optogenetics, the mice's preference for the low-risk, low-cost option changed and they began choosing the high-risk, high-cost option.
What researchers did in the current study is quite similar except instead of the optogenetic manipulation, the researchers subjected the mice to stress every single day for two weeks. Before the mice were stressed out, they chose the dimmer side of the maze practically half the time and continued to choose it as researchers increased the chocolate concentration on that side.
When the chronically stressed mice were faced with the same choice, they kept on choosing the side with the bright lights even after the chocolate concentration on the dimmer side has been increased, showing reactions similar to optogenetically manipulated mice. In addition, the researchers found that the effect could last for months once the high-risk, high-cost behavior begins.
Excitation, Addiction, And Possible Reversal
"It's as though the animals had lost their ability to balance excitation and inhibition in order to settle on reasonable behavior," said Ann M. Graybiel, one of the authors of the study.
Fortunately, just as the researchers were able to induce this behavior with optogenetic manipulation and chronic stress, they were able to reverse and restore normal decision-making by stimulating high-firing neurons and suppressing striosomes. This suggests that it's possible to reverse the impulsive behavior brought about by stress such as in the case of addiction.
"This state change could be reversible, and it's possible in the future that you could target these interneurons and restore the excitation-inhibition balance," said Alexander Friedman, lead author of the paper.
The study is published in the journal Cell.