Nav: Home

Closer threats inspire a more primitive kind of fear

June 29, 2020

DURHAM, N.C. - Your brain handles a perceived threat differently depending on how close it is to you. If it's far away, you engage more problem-solving areas of the brain. But up close, your animal instincts jump into action and there isn't as much reasoning, like when the guy at the haunted house jumps up right next to you.

And that, according to a new study using virtual reality to make threats appear near or far, is probably what makes it harder to extinguish the fear of a close-up threat and more likely that you'll have some long-term stress from the experience.

It has been shown that traumatic events that touch the body, like rape and other physical assaults, are more strongly associated with post-traumatic stress disorder than are traumas viewed at some distance.

Now, thanks to a clever adaption that put research subjects into a 3D virtual reality environment while their brains were being scanned by an MRI machine, researchers have seen just how the circuitry of those brain responses differ.

"Clinically, people who develop PTSD are more likely to have experienced threats that invaded their personal space, assaults or rapes or witnessing a crime at a close distance. They're the people that tend to develop this long-lasting threat memory," said Kevin LaBar, a professor of psychology and neuroscience at Duke University who is the senior author on a paper appearing this week in the Proceedings of the National Academy of Sciences.

"We've never been able to study that in the lab because you have a fixed distance to the computer screen," LaBar said.

But Duke graduate student Leonard Faul and postdoc Daniel Stjepanovic figured out a way to do it, using a 3D television, a mirror and some MRI-safe 3D glasses.

"It's like an IMAX experience," LaBar said. "The threatening characters popped out of the screen and would either invade your personal space as you're navigating this virtual world, or they were farther away."

The VR simulation put 49 study subjects into a first-person view that had them moving down either a dark alley or a brighter, tree-lined street as they lay in the MRI tube having their brains scanned. Ambient sound and visual backgrounds were altered to provide some context for the threat versus safe memories.

On the first day of testing, subjects received a mild shock when the "threat avatar" appeared, either two feet away or 10 feet away, but not when they saw the safe avatar at the same distances.

The data from the first day showed that near threats were more frightening and they engaged limbic and mid-brain "survival circuitry," in a way that the farther threats did not.

The following day, subjects encountered the same scenarios again but only a few shocks were given initially to remind them of the threatening context. Once again, the subjects showed a greater behavioral response to near threats than to distant threats.

"On the second day, we got fear reinstatement, both near and far threats, but it was stronger for the near threat," LaBar said.

Tellingly, the nearby threats that engaged the survival circuits also proved harder to extinguish after they no longer produced shocks. The farther threats that engaged more higher-order thinking in the cortex were easier to extinguish. The near threats engaged the cerebellum, and the persistence of this signal predicted how much fear was reinstated the next day, LaBar said. "It's the evolutionarily older cortex."

The more distant threats showed greater connectivity between the amygdala, hippocampus and ventral medial prefrontal cortex and the areas of the cortex related to complex planning and visual processing, areas the researchers said are more related to thinking one's way out of a situation and coping.

Understanding the brain's response to trauma at this level might point to new therapies for PTSD, LaBar said.

"We think that the cerebellum might be an interesting place to intervene," he said. "Clinically, it's a new interventional target. If you can somehow get rid of that persistent threat representation in the cerebellum, you might be less likely to reinstate (the fear) later on."
-end-
This research was funded by the National Science Foundation (BCS 1460909).

CITATION: "Proximal Threats Promote Enhanced Acquisition and Persistence of Reactive Fear-Learning Circuits," Leonard Faul, Daniel Stjepanovic, Joshua Stivers, Gregory Stewart, John Graner, Rajendra Morey and Kevin LaBar. Proceedings of the National Academy of Sciences, June 29, 2020. DOI: 10.1073/pnas.2004258117

Duke University

Related Brain Articles:

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.
Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.
An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.
Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.
Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.
Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.
Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.
BRAIN Initiative tool may transform how scientists study brain structure and function
Researchers have developed a high-tech support system that can keep a large mammalian brain from rapidly decomposing in the hours after death, enabling study of certain molecular and cellular functions.
Wiring diagram of the brain provides a clearer picture of brain scan data
In a study published today in the journal BRAIN, neuroscientists led by Michael D.
Blue Brain Project releases first-ever digital 3D brain cell atlas
The Blue Brain Cell Atlas is like ''going from hand-drawn maps to Google Earth'' -- providing previously unavailable information on major cell types, numbers and positions in all 737 brain regions.
More Brain News and Brain Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.