An unpublished study recently published in the journal brain stimulation measures changes in the human brain’s response to a perceived threat following noninvasive stimulation of the nervous system via the vagus nerve. The findings have implications for the development of treatments for post-traumatic stress disorder (PTSD) and other mental health conditions, as well as for increasing alertness and attention during learning.
“Although our sample size is small, our results are intriguing,” said the study’s lead author, Dr. Imanuel Lerman of the Qualcomm Institute (QI) at UC San Diego, School of Medicine. and the Jacobs School of Engineering as well as the VA Center of Excellence. for stress and mental health. “Participants’ vagus nerve stimulation intensified their reaction to negative images and decreased their reaction to positive images. This supports the idea that there is an additive link between vagus nerve stimulation and norepinephrine signaling, which is essential for fight-or-flight responses, in the brain. . »
One of the body’s primary means of communication with the brain, the vagus nerve plays a vital role in regulating the “fight or flight” response. While previous research has indicated that stimulating this nerve improves attention, reduces reaction time, and increases learning, no one has tested how this technique affects the body’s response to an emotionally charged stimulus.
The research team selected 24 healthy adults to receive either a placebo treatment or noninvasive stimulation of the vagus nerve where it runs parallel to the carotid artery.
These volunteers entered an fMRI machine and performed a simple task of pressing a button on a wearable device in response to a blue circle or square being displayed. All participants were then either told that the shape would turn red to signal the imminent appearance of an upsetting image (i.e. a war image), accompanied by a high-pitched tone, or green to signal an image pleasant incoming (i.e. a photo of a calm lake), accompanied by a low, soothing tone.
The researchers recorded the difference in the participants’ reaction time, brain activity and blood oxygen levels. Volunteers who received vagus nerve stimulation showed significantly faster reaction times during neutral and emotionally charged tasks. However, people who received vagus nerve stimulation had stronger brain responses to negative/disturbing images and diminished responses to pleasant images when measured with fMRI. The reverse was true for the control group.
“The study results represent a first step toward understanding how noninvasive vagus nerve stimulation could be used effectively as a tool to treat patients with PTSD, generalized anxiety, and other disorders that involve an increased response to perceived threats,” Lerman said.
In addition to Lerman, the other authors of the study, “Effects of Noninvasive Cervical Vagus Nerve Stimulation on Reaction Time and Valence,” were Ruth Klaming, Andrea Spadoni, Dewleen Baker, and Alan Simmons, all of the Department of Psychiatry, UC San Diego School of Medicine and the VA Center of Excellence for Stress and Mental Health, VA San Diego Healthcare System.
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Materials provided by University of California–San Diego. Original written by Xochitl Rojas-Rocha. Note: Content may be edited for style and length.