Humanity spends an inordinate amount of time and resources building new types of guns used to do terrible things. Now, finally, it seems like a team of researchers who published their findings in Science Advances has developed a system that blasts people with sound waves that temporarily dampen their fear responses.
The work, led by scientists at Radboud University, targeted the amygdala, the small structure thought to be the engine that powers our brain’s fear responses. It’s the part of the brain that helps you quickly learn some lessons from danger. More importantly, it keeps those lessons lingering long after the threat is gone. Unfortunately, in disorders like PTSD, that lingering lesson becomes a problem that traps someone in a constant state of fear.
Using transcranial ultrasound stimulation, the researchers sent a focused, low-intensity series of sound waves through the skull to suppress amygdala activity in healthy participants for only a few moments. Then they ran a controlled fear-learning experiment in which images of snakes were paired with mild electric shocks. The point of it was to teach the brain to fear something, and then see how, or if, it can unlearn that fear.
Scientists Just Got Closer to Turning Off Fear in the Brain
The team found that when they dampened the amygdala with the sound waves, participants were slower to form fear associations in the first place. Once the threat disappeared, they let go of the fear much faster than they would have before. Now, you’d think this might have the negative consequence of making us forget to fear a scary thing in the first place.
Thankfully, the researchers found that the participants’ overall ability to learn a lesson from fear wasn’t affected, only the part directly tied to the threat. That means the brain didn’t get worse at learning; it just got less attached to fear.
The team conducted a follow-up experiment, this time on the hippocampus, a nearby brain region that powers memory. That one had no effect. That was a valuable test because it ruled out the idea that any brain stimulation would do the same thing. It doesn’t, so that means this is specifically about the amygdala.
There was one catch, though: participants whose amygdala activity was suppressed also formed less accurate memories about the threats. The researchers found that they tended to overstate how often danger had occurred, which is itself another valuable lesson because it suggests that the amygdala allows us to calibrate our fear responses.
This amygdala-penetrating sound wave technology could have huge implications for those suffering from PTSD and anxiety disorders, which are, at their core, all about fear responses refusing to shut down. Should this technique prove viable in subsequent testing, it could make the brain less efficient at holding on to fear in the first place, or maybe just better at letting go.
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