Sometimes, our small fears blossom into intense anxieties with dire consequences. If your anxiety over talking to your family over the holidays threatens to turn happy gatherings into stress-inducing horror shows, we have good news. A new study suggests a comforting sight or sound could be exactly what your brain needs to help you put things into perspective.
“Safety signals,” or objects associated with safety, can help reduce fear even when we’re confronted with something scary, finds a new study in mice and humans. The finding is perhaps no surprise: a comforting token may make you feel just that — comforted. But the scientists take it further: just the sight or sound of a “safety signal” changes the way the brain reacts to fear by bringing a key brain area, the ventral hippocampus, into play.
Targeting this “alternative neural circuit” could help people reduce their feelings of fear, opening up a new way to fight anxiety disorders. More work is needed before the technique is tested in people with anxiety says Paola Odriozola, a graduate student at Yale University and the study’s co-first author.
“As a method of reducing fear that could provide initial relief, judicious use of safety signals may help patients to better engage with existing therapies that focus on exposure to the patient’s fears,” Odriozola tells Inverse.
The paper was published this week in Proceedings of the National Academy of Sciences.
How a “safe signal” reduces fear
A “safe signal” may offer an alternative to cognitive behavioral therapy, which psychologists already use to help people tackle outsized fears. The therapy uses a process called “fear extinction.” If you’re afraid of something, therapists will expose you to that fear in small doses and in a controlled environment. Eventually, the new, positive memory eclipses the old, fearful one.
But despite the therapy, the fearful memory is still there — “competing” with the new safe memory, the researchers say. A safety signal has no fearful memories attached to it, by contrast. Instead, it may tamp down fear responses by changing the way the brain responds to threats.
Scientists exposed both human and murine subjects to a “threat cue” — either a visible shape or a sound followed by mild shock. Study participants were also given a “safety” signal — a tone or a shape that wasn’t associated with a painful experience. The team also took fMRI scans of their human participants’ brains during this process.
"This reduction was immediate."
In the sample of 22 humans, their brains showed the fewest signs of fear when they were exposed to the safety signal, and the most when they were exposed to the threatening one. But being given the safe signal simultaneously with the threat cue actually dampened their fearful response.
“This reduction was immediate, contrasting with the lengthy training procedures required for extinction-based therapies,” Heidi Meyer, a postdoctoral associate at Weill Cornell Medical and study co-author, tells Inverse.
The fMRI scans reveal a possible reason why. The brain area known as the ventral hippocampus, which is associated with assessing threats, was most active when when study participants saw both the danger signal and the safety signal at once. The region also appeared to interact with different areas of the brain as compared to when people only saw the threat without a safety signal. When they saw both signals, there were higher levels of connectivity between the ventral hippocampus and the dorsal anterior cingulate cortex.
Safety signals may target that neural pathway, which then dampens fear, the authors suggest.
There’s still a lot to learn about safety signals and how well they might work for people who really do have anxiety. Safety signals could also have a downside, says Odriozola. A child’s over-reliance on a parent may count as a safety signal, but embracing it may not be helpful in the long run, she says.
“Although these might interfere with the ability to reduce fear in the longer term, our study might help to understand how they operate,” she says.
And if you are already feeling anxious about the holiday period, don’t fear: Figuring out your own safety signal shouldn’t be hard, Odriozola says. It could be as simple as a piece of music, a toy, or a person who makes you feel at home — whether they are family or not.
Heightened fear and inefficient safety learning are key features of fear and anxiety disorders. Evidence-based interventions for anxiety disorders, such as cognitive behavioral therapy, primarily rely on mechanisms of fear extinction. However, up to 50% of clinically anxious individuals do not respond to current evidence- based treatment, suggesting a critical need for new interventions based on alternative neurobiological pathways. Using parallel human and rodent conditioned inhibition paradigms alongside brain imaging methodologies, we investigated neural activity patterns in the ventral hippocampus in response to stimuli predictive of threat or safety and compound cues to test inhibition via safety in the presence of threat. Distinct hippocampal responses to threat, safety, and compound cues suggest that the ventral hippocampus is involved in conditioned inhibition in both mice and humans. Moreover, unique response patterns within target- differentiated subpopulations of ventral hippocampal neurons identify a circuit by which fear may be inhibited. Specifically, ventral hippocampal neurons projecting to the prelimbic cortex, but not to the infralimbic cortex or basolateral amygdala, were more active to safety and compound cues than threat cues, and activity correlated with freezing behavior in rodents. A corresponding distinction was observed in humans: hippocampal–dorsal anterior cingulate cortex functional connectivity—but not hippocampal–anterior ventromedial prefrontal cortex or hippocampal–basolateral amygdala connectivity—differentiated between threat, safety, and compound conditions. These findings highlight the potential to enhance treatment for anxiety disorders by targeting a neural mechanism through safety signal learning.