We can easily identify emotion through facial expressions — we “know” what happy, sad, surprised and angry look like, so to speak. We also know that changes in brain activity underlie emotional reactions — when we see something upsetting, various brain networks light up.
But we’ve had less luck figuring out what, exactly, being upset looks like in the brain. With varying success, over the past decade, neuroscientists and psychologists have used neuroimaging tools to construct neural pictures of different emotions. Most fall short. For one, scientists have focused too much on the role of certain brain regions, which may serve multiple functions (making it impossible to differentiate, for example, our response to novelty and our response to pain — both are stimuli). Other studies have failed to distinguish between explicitly emotional responses and heightened feelings, also called salience.
But researchers at Dartmouth College have announced some much-needed headway. They’ve identified a distinct pattern of brain activity that predicts negative emotional responses to disturbing images. In other words, they believe they’ve made a first real step in figuring out how to read the brain, just as we read faces.
For this study, published in PLoS Biology, researchers scanned the brains of 183 adults as they viewed a series of images both negative (e.g., bodily injury, violence) and neutral (e.g. inanimate objects). While viewing some pictures, participants were told to embrace their natural emotional responses. Viewing others, they were told to suppress their reactions. The participants also rated their emotional responses to the images.
Nearly 90 percent of the time, the signature brain pattern aligned with participants’ ratings of their feelings. To ensure the patterns indicated emotional pain (and not physical pain, too), researchers also scanned the participants’ brains as they were subjected to painful heat. As researchers predicted, the signature brain pattern did not activate during these tests.
Why is this useful? Scientists have been plugging away, trying to use neuroimaging to measure emotions objectively. Despite hundreds of studies, we've struggled to scientifically assess the validity, and perhaps even intensity, of reported feelings. And though these findings correlate only to responses provoked by images and environmental stimuli, it’s possible that more research can also dig into other emotional triggers, such as recollection of painful memories. The possibilities for trauma treatment are immense.