Walking down the street by yourself late at night, until in the distance you see a person standing in the shadows. With a pounding heart, you ponder your decision. Do you cross the street? Do you turn around? Or do you ignore the unsavory type?
Now compare this scenario to the following. You are walking down that same street again, but this time you are startled by the sound of squealing tires. In the corner of your eye you see a car coming toward you, and you can barely jump aside in time.
Both scenarios describe an instance in which your brain perceives danger. Yet there are important differences between the types of danger. In the first case, the source of possible danger is at a distance, giving you time to think out a strategy. In the second case, there was no time to think; you had to act immediately. This suggests that fear and danger are not regulated by just one network of brain regions, as is often assumed. In a recent study, American scientists show that two different brain networks are indeed involved. The cognitive-anxiety network is responsible for processing fear at a distance, and consists of the hippocampus, posterior cingulate cortex and ventromedial prefrontal cortex. The reactive-anxiety network is engaged when immediate action is required, and consists of the midcingulate cortex and the periaqueductal gray.
Game in the scanner
Participants in this study were placed in an MRI scanner in which their brain activity could be measured. Since it is not ethical to put these volunteers in serious danger in the lab, a video game was chosen to simulate danger. In the game, the goal was to hold a small triangle in the middle of the screen for as long as possible. The longer this succeeded, the more money could be earned. Unfortunately, there were two colored circular bad guys programmed, and this villain was targeting the triangle's life. The red round robber could only attack at close range, so you could see him coming from afar. The blue villain, on the other hand, was able to attack from a greater distance, so you had less time to react.
The researchers saw in the brain data that when the dangerous blue enemy appeared on the scene, the reactive-anxiety network activated, while activity in the cognitive-anxiety network actually decreased. When the less dangerous red circle made its entrance, the cognitive-anxiety circuitry was in full action, and the reactive-anxiety network was not.
This study shows that the brain has more than one fear network. Depending on the context of danger, the brain uses a different neural pathway to act. This is important information for future treatments for anxiety disorders, for example.
See a funny visual summary of the study here:
This article is a previously published Brainmatters article written by Job van den Hurk (19-3-18)
Reference: Qi, S., Hassabis, D., Sun, J., Guo, F., Daw, N., & Mobbs, D. (2018). How cognitive and reactive fear circuits optimize escape decisions in humans. Proceedings of the National Academy of Sciences of the United States of America, 115(12), 3186–3191. https://doi.org/10.1073/pnas.1712314115