For some people, anxiety is a bad, but fleeting experience. But for others, it can rule day-to-day lives—and even lead to the wrong decisions.
Now, a new study shows that anxiety disengages a region of the brain called the prefrontal cortex (PFC), which is critical for flexible decision-making.
By monitoring the activity of neurons in the PFC while anxious rats had to make decisions about how to get a reward, scientists made two discoveries: First, anxiety leads to bad decisions when there are conflicting distractors present—and second, bad decisions influenced by anxiety involve numbing of PFC neurons.
The new findings indicate that anxiety has an exquisitely selective effect on neuronal activity that supports decision-making, says Bita Moghaddam, professor of neuroscience at the University of Pittsburgh.
Until now, scientists have mostly studied anxiety in animal models in the context of fear and measured how brain cells react to a threatening situation. But human anxiety is insidious, not merely because of how the person feels, but also because it can interfere with nearly all aspects of daily life, including making decisions, Moghaddam says.
The researchers studied this aspect of anxiety by monitoring the activity of a large number of neurons as rats made decisions about which choice was most optimal for receiving a reward. They compared behavior and neuronal activity in two groups: one group that had a placebo injection and another that got a low dose of an anxiety-inducing drug.
As with many people who suffer from anxiety but go through day-to-day life and make decisions, the anxious rats completed the decision-making task and, actually, did not do too badly.
But they made far more mistakes when the correct choice involved ignoring distracting information.
“A brain locus of vulnerability for these anxiety-induced mistakes was a group of cells in the PFC that specifically coded for choice. Anxiety weakened the coding power of these neurons,” Moghaddam says.
“We have had a simplistic approach to studying and treating anxiety. We have equated it with fear and have mostly assumed that it over-engages entire brain circuits. But this study shows that anxiety disengages brain cells in a highly specialized manner.”
The findings appear in the Journal of Neuroscience.
Source: University of Pittsburgh