Study Says Different Parts of Our Brain Handle Immediate and Distant Threats

A year or so ago, I went to the movies with some friends to see The Purge: Election Year. For those of you who haven’t seen this movie, it’s pretty disturbing and unsettling. The whole series is about an annual “purge,” in which all criminal activity is legal for 12 hours—and yes, that includes murder. Each installment is essentially 90 minutes of the characters trying to survive, but most often failing to do so. Oh, and I forgot to mention, the “bad guys” wear scary masks. So, to say the least, these movies creep me out and just five minutes in I’m looking away from the screen. It’s then that I notice a man hunched over a few seats behind me. He’s alone and his face is hidden beneath a dark hood.

I’m now distracted from the scary movie by the scary man sitting behind me. Why is he wearing that hood? Why is he seeing such a creepy movie by himself? Why is he sitting in the very back row of the theater? My mind is basically spiraling out of control, as I try to sort through possible explanations as well as brainstorm a course of action for if things go south. Then, all of a sudden the theater is covered in flashing red lights and an alarm is sounding overhead. Without even thinking, I fly across everyone still seated in my row and dart out the door.

I faced two threatening situations that night: the first was the threat of the strange, mysterious man sitting in the back of the theatre, and the second was the threat of a fire. However, there were major differences in the two threats that I faced—obviously how I reacted, but also how my brain processed each threat, according to new research published in PNAS. This study “How cognitive and reactive fear circuits optimize escape decisions in humans” has found that there are two different areas of the brain involved in fear processing.

The first threat I experienced is known as a distant threat, whereas I had more time for thinking and strategizing. These types of threats are processed by the cognitive-fear circuit, which involves the hippocampus, the posterior cingulate cortex, and the ventromedial prefrontal cortex. The second threat I experienced was an immediate threat and therefore demanded a quick reaction. These types of threats are handled by something called the reactive-fear circuit, which consists of connections near the center of the brain between two structures: the periaqueductal gray and midcingulate cortex.

According to Dean Mobbs, Assistant Professor of Cognitive Neuroscience and co-author of the study, these circuits work as a seesaw: when activity in one circuit goes up or increases, activity in the other goes down or decreases. And it’s the immediacy of any given threat that determines which way the seesaw falls. This happens so that your brain can react appropriately and effectively to the type of threat. Mobbs explains what would happen if your circuits didn’t teeter this way: “If there’s a tiger in the room, and you’re trying to decide whether you should move left or move right, you’re going to end up being eaten while you’re still thinking about how to best escape.”

To reach their findings, Mobbs and his research team performed fMRIs on study subjects while they played a “virtual predator” video game. This game required players to keep their character in a particular spot on the screen—and the longer they could keep them there, the more money they were promised. Meanwhile, one of three predators moved around the screen and threatened to attack. If the predator attacked while the player remained in the given spot, then they lost all of the money earned during that session and received a mild electric shock meant to simulate the physical danger the predator posed.

The researchers found that when a player was challenged by the most dangerous predator, the activity in their brain’s reactive-fear circuit (which handles immediate threats) increased, while the activity in the cognitive-fear circuit (which handles distant threats) lessened. And when a player was threatened by a less dangerous predator, the opposite happened: activity in the cognitive-fear circuit increased, while it decreased in the reactive-fear circuit.

In conclusion, Mobbs says, “we need to reconsider the idea that only one brain region is involved in fear,” as this study, “shows that fear is not one thing. It’s contextually based, and it can be conscious or subconscious.” Furthermore, these findings may provide additional insight into how neural circuits go haywire in people with panic and anxiety disorders that could ultimately result in better treatments for these individuals.

Sources:
CalTech (2018, March 6). Brain Has Separate ‘Fear Circuits’ for Dealing with Immediate and Distant Threats. NeuroscienceNews. Retrieved March 6, 2018 from http://neurosciencenews.com/fear-threat-neural-networks-8594/

Qi, S., Hassabis, D., Sun, J., Guo, G., Daw, N., & Mobbs, D. (2018, February 8). How Cognitive and reactive fear circuits optimize escape decisions in humans. PNAS. Retrieved on March 6, 2018 from http://www.pnas.org/content/early/2018/03/02/1712314115

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