Scared of spiders? Heights? Public speaking? They activate different parts of the brain, research shows

What scares you the most? Maybe he’s teetering precariously on the edge of a skyscraper; maybe it’s a giant, hairy tarantula crawling across your laptop keyboard. Maybe it’s giving a wedding toast and telling a joke that doesn’t make anyone laugh.

For a long time, mainstream research assumed that responses to these three scenarios occurred in the same way in the brain.

“There’s this story we have in the literature that the regions of the brain that predict fear are things like the amygdala, or the orbital frontal cortex area, or the brainstem,” says Ajay Satpute, associate professor in psychology at Northeastern University. “These are thought to be part of a so-called ‘fear circuit’ that has been a very dominant pattern in neuroscience for decades.”

In early October 2024, Satpute and colleagues published new research that challenges this persistent pattern. In a study published in The Journal of Neuroscience researchers used MRI scans to observe brain activity when presented with three distinct scenarios thought to evoke different types of fear: fear of heights, fear of spiders, and fear of “social threats” (public speaking, confrontations with the police).

And contrary to prevailing scientific wisdom, the neural response to each type of scenario activated different areas of the brain, rather than following a single pattern.

“Much of the debate over the nature of emotion concerns the uniformity or heterogeneity of representation of particular emotion categories,” the study states.

“We show that the overwhelming majority of brain regions that predict fear only do so in certain situations. These results have implications for generalizing fear findings across species, translational models of fear and anxiety and the development of neural signatures of fear.”

The researchers wanted to test hypotheses about how fear works in the brain, because in neuroscience, AI and machine learning are increasingly used to develop models that can predict particular emotions based on patterns of emotion. brain activity.

“Most of these approaches assume that there is a single model that underlies the brain behavioral relationship: there is a single model that predicts disgust. There is a single model that predicts anger,” says Satpute. “Well, if that’s true, then such a pattern should be apparent for different varieties of fear.”

To test this, the study asked 21 participants to complete surveys about things that scared them, then monitor their brain activity via MRI while they watched videos depicting first-person viewpoints of distinct scenarios and scary: looking at steep ledges while hiking; give a public speech; being approached by a large hairy spider.

“We tried to find videos of really scary spiders,” says Satpute, who is a little scared of them himself. “Because I don’t want a neural predictive model that says you’re looking at a spider.” I want a predictive neural model that says “you feel fear”.

After each video, participants self-rated their levels of fear, valence (the degree to which an experience is pleasant or unpleasant), and arousal on a questionnaire.

Although based on a small sample, the study revealed two things: Fear responses occurred in more brain regions than expected. But not all brain regions responded to all three situations.

“The amygdala, for example, seemed to contain information predicting fear in the context of heights, but not in some other contexts,” notes Satpute. “We don’t see these so-called ‘classic threat zones’ involved in predicting fear in all situations.”

The experiment is part of a series of studies from Satpute’s lab that investigate the bodily mechanisms of fear, reinforcing the concept that not all fears are the same. In 2021, the group published a study that examined autonomic responses to distinctive frightening scenarios, measuring things like sweat and cardiac output. There too, different fears – heights, being chased by the police – manifested differently.

In future studies, Satpute hopes to confirm the findings with a larger sample, looking more closely at the role demographic factors such as gender and age might play. He says such findings, while preliminary, could play a role in how fear and anxiety disorders are treated.

“When we look at the brain and the neural correlates of fear, part of the reason we want to understand is to be able to intervene on it,” he says. “Our findings suggest that interventions may also need to be tailored to the person and situation.”

This could affect behavioral therapies, but also, much later, pharmacological therapies.

“Drug therapies targeting a particular circuit work, but only for about fifty percent of people,” says Satpute. “It’s not entirely clear why. Our research offers at least one explanation: The regions of the brain that will be important for any emotional experience will vary depending on the person and the situation. If you focus only on what is common, you are ignoring a lot of things.”

This story is republished courtesy of Northeastern Global News news.northeastern.edu.