Neuroscientists have developed a new technique for analyzing brain patterns that may help train people to reduce their fearful responses. The approach could have implications for treating people with depression, dementia, and anxiety disorders, such as post-traumatic stress disorder (PTSD).
The method, developed by neuroscientists at the University of California, Los Angeles (UCLA), is described in the journal Nature Human Behaviour.
For the study, the scientists found that they could reduce the brain’s fear response using a procedure called “decoded neurofeedback.” This method involves identifying complex patterns of brain activity linked to a specific memory, and then giving feedback to the participant — for example, in the form of a reward — based on their brain activity.
The scientists tested this technique on 17 college students in Japan. While undergoing functional magnetic resonance imaging, or fMRI, students were shown patterns of vertical lines in four colors — red, green, blue, and yellow. The blue and yellow images were always shown without shocks, but the red and green patterns were often accompanied by a small electrical shock administered to their feet.
As a result of the shocks, the participants’ brain patterns naturally began to show fear toward the red and green images. But the scientists soon discovered that they could use decoded neurofeedback to lessen the students’ fear of the red pattern.
They did this by giving the students a small cash reward each time they spontaneously thought about the red lines — they gave no rewards for thinking about the green lines. The scientists could determine in real time which color the students were thinking about based on their brain activity.
The next day, the scientists tested whether the students still elicited a fear response to the vertical lines. The red pattern, which had been frightening because it was paired with shocks, became less frightening now that it was paired with a positive outcome. With the new addition of the reward, researchers found that participants perspired much less than they did previously while viewing the red lines, and their brain’s fear signal, centered in the amygdala, was significantly reduced.
“After just three days of training, we saw a significant reduction of fear,” said senior author Hakwan Lau, a UCLA associate professor of psychology. “We changed the association of the ‘fear object’ from negative to positive.”
Importantly, the students were not told what they had to do to earn the money — only that the reward was based on their brain activity and that they should try to earn as much money as possible. And each time they were informed that they had just won some money, their brains showed more of the same pattern that had just won them the cash reward.
Although the subjects tried to figure out which of their thoughts were being rewarded — some guessed humming music or thinking about a girlfriend, for example — none accurately guessed how they had actually earned the money and none recognized that the scientists had successfully lowered their fear of the red lines.
“Their brain activity was completely unconscious,” Lau said. “That makes sense; a lot of our brain activity is unconscious.”
Participants did still register fear on their fMRI scans when they saw the green pattern because, without the financial rewards, they still primarily associated the color with shocks.
The findings could help improve upon standard behavioral therapy, in which a person who is afraid of a certain object is exposed to photos of that object, or even the object itself — which can be frightening enough that many people cannot complete treatment.
Lau said using “unconscious fear reduction,” like in the experiment, could be more effective in many cases.