What if we could turn off fear? When it comes to certain stimuli, researchers from Germany believe their electrical stimulation method could do just that, preventing the fear response that happens when some people see things they are afraid of from returning. By zapping specific regions of the brain, the participants no longer had that involuntary fear reaction when exposed to their phobia stimuli after being trained not to, which could mark a significant breakthrough in trauma and anxiety therapies.
As much as it seems counterproductive, fear is an essential part of humans’ ability to stay alive. Certain phobias, such as snakes and spiders, are thought to have an evolutionary origin, dating back to a time when those who stayed away from venomous creatures were more likely to survive. Fear raises our heart rate, making us more alert in dangerous situations, and can help in making fight or flight decisions that may mean the difference between life or death. We store information about what needs to be feared inside our memory, so that we may respond quickly to fear cues next time – this is called the “fear memory recall”.
Sometimes, we learn that something may be a threat, but constant exposure to linked cues teaches us that we no longer have anything to fear and our fear response to those cues no longer happens involuntarily – this is called “fear extinction”.
However, fear extinction doesn’t always occur, particularly for things such as traumatic events. Despite repeated exposure to cues that might show there is nothing to fear, our body still reacts the same way, and this can contribute to mental disorders.
“Fortunately, however, we know the brain areas underlying fear extinction quite well and therefore wanted to investigate whether a non-invasive electrical stimulation of these areas might improve the long-term reduction of fear,” said study author Christoph Szeska of the University of Potsdam, according to PsyPost.
“This might open up new avenues for improving treatment of mental disorders.”
To test whether non-invasive transcranial stimulation could help, the researchers delivered direct current to the ventromedial prefrontal cortexs of a group of 20 students, while a control group of another 20 received a sham experiment. It was double-blind, meaning no one knew which students would be getting the electricity except the researchers not conducting the experiment.
First, each student had an uncomfortable (but “not painful”) shock to one hand, as well as a startling noise, to elicit a shock response and try to induce fear. The activity of their eyes, their heart rate, and a questionnaire were used to test how much the students were expecting the next shock. These shocks were linked to them seeing one of two pictures – they got shocked when they saw one, but not when they saw the other. This created a fear memory recall for that picture.
Then, the researchers tried to extinguish this fear by showing the images without the shocks. They then used electrical brain stimulation (tDSC) before showing them the pictures again and measuring their response. Those that received the stimulation reported expecting the electric shocks, but their bodies were doing something different – compared to the control group, they did not experience the involuntary fear response. In the sham group, their bodies were still bracing for the shock.
While limitations still need to be addressed, the study hints at how powerful non-invasive simulation could be at eliminating the return of fear responses in trauma patients, if the underlying mechanisms are further identified. The researchers now hope to optimize the procedure and push it to clinical trials.
The research was published in Translational Psychiatry.