Findings from a study published in Nature Neurosciencereveal distinct patterns for how the brain and body respond when learning about danger and safety. The findings could help explain why post-traumatic stress disorder (PTSD) symptoms can be severe for some people, but not others.
In the study, combat veterans with varying levels of PTSD were given a reversal learning task. Images of 2 mildly angry human faces were paired with a mildly aversive stimulus. In the first phase of the task, participants learned to associate one face with the mildly aversive stimulus. In the second phase, participants learned to associate the other face with the stimulus.
Regardless of the level of PTSD symptoms, all participants were able to perform the reversal learning. But when researchers examined the data closely, they found that when highly symptomatic veterans were given cues they didn’t expect, they responded with greater corrections in several brain regions and in their physiological arousal (eg, skin conductance responses).
“What these results tell us is that PTSD symptom severity is reflected in how combat veterans respond to negative surprises in the environment—when predicted outcomes are not as expected—and the way in which the brain is attuned to these stimuli is different,” said Daniela Schiller, PhD, associate professor of psychiatry and neuroscience at the Icahn School of Medicine at Mount Sinai, New York City. “This gives us a more fine-grained understanding of how learning processes may go awry in the aftermath of combat trauma and provides more specific targets for treatment.”
Matthew Varon, MD; and Pedro M. Machado, MD, PhD
Jonathan R. Brent, MD, PhD; and Senda Ajroud-Driss, MD