The way we experience emotions has remained an enigma to us, despite various attempts to shed some light on this part of our brain. The quest to understand our “emotional brain” has inspired hundreds of studies, many of which involve neuroimaging of the brain. Previously, none of these studies were very useful in terms of indicating emotional experiences. The reason for this is that specific, sensitive “brain signatures” must be developed and applied to individuals to yield information about their personal experiences. Thanks to a Dartmouth researcher and his colleagues, we just got a lot closer to figuring out our emotions.

The new study, published in PLOS Biology, aimed to develop a brain signature that can predict the intensity of negative emotional responses to negative images. This signature would then be tested in how it can generalize across different participants, images, and even pain. Then, researchers would examine the neural circuitry required to predict negative emotional experience.

Luke Chang, an assistant professor in psychological and brain sciences at Dartmouth and lead author of the study, looked at 182 participants who were shown negative photos (including things like acts of aggression, bodily harm, car wrecks, hate groups, and human feces) and neutral photos. Thirty additional participants were also subjected to painful heat.

The team was able to utilize brain imaging, among other techniques, to identify a neural signature of negative emotion — a single neural activation pattern, active across the entire brain — that could accurately predict how negatively a person feels toward unpleasant images.

"This means that brain imaging has the potential to accurately uncover how someone is feeling without knowing anything about them other than their brain activity," Chang said in a press release. "This has enormous implications for improving our understanding of how emotions are generated and regulated, which have been notoriously difficult to define and measure."

The study had an incredible accuracy rate of about 90 percent, and it also utilized a large sample size of adult participants. Subjects were also tested across multiple psychological states, which allowed researchers to determine the specificity and sensitivity of their brain model.

"We were particularly surprised by how well our pattern performed in predicting the magnitude and type of aversive experience," Chang said. "There is an intuition that feelings are very idiosyncratic and vary across people. However, because we trained the pattern using so many participants … we were able to uncover responses that generalized beyond the training sample to new participants remarkably well."

Source: Chang L, Gianaros P, Manuck S, Krishnan A, Wager T. A Sensitive and Specific Neural Signature for Picture-Induced Negative Affect. PLOS Biology. 2015.