The modern world is full of distractions, from YouTube videos that manage to consume the whole workday to the cell phone calls that turn safe drivers into road hazards. According to a bicoastal cadre of researchers, plain ol' emotions can be distractions that are just as problematic.

"People with post-traumatic stress disorder [PTSD], general anxiety disorder, and very severe depression just can't quite clear their minds of emotional stimuli," said Amit Etkin, a psychiatrist at Stanford University.

In a study published in the Sept. 21 issue of Neuron, Etkin and colleagues at Columbia University explored how the brain handles emotional distraction.

They found that a structure at the front of the brain plays an active role in resolving emotional conflict. It accomplishes this task by diminishing activity in the amygdala, which is known to process emotion

While undergoing fMRI, healthy volunteer subjects viewed a series of images that paired a face expressing an emotion with a word labeling that emotion. Some images, such as a smiling face labeled with the word "happy," were congruent. Others were incongruent—a smiling face labeled "fear," for instance. For each image, the subjects were asked to ignore the word and identify the emotion expressed on the face.

The researchers found that just viewing the images was enough to activate the amygdala, which is known to process emotion. When subjects tried to identify the emotions in incongruent images, however, parts of a structure known as the anterior cingulate cortex (ACC) were also activated. The brain scans revealed that the activation of the ACC, which is involved in cognitive processing, suppressed activity in the amygdala.

It is this dampening of the amygdala by the ACC, the researchers conclude, that allows people to filter out emotional stimuli that distract from cognitive tasks.

The researchers also noted that when an incongruent image was preceded by another incongruent image, subjects had an easier time resolving the conflict. Etkin theorizes that this effect is the result of priming the ACC to more quickly filter out distracting emotional labels.

The finding has implications for the diagnosis of psychological disorders in which people suffer from intrusive emotions. For instance, Etkin says this feedback loop may lead to a greater understanding of some patients with PTSD, who are believed to have both underactive ACCs and overactive amygdalas.

"Using this kind of paradigm may be a way to test for emotional control," Etkin said, adding that it could also serve as a diagnostic "probe" to determine which patients might respond best to antidepressants, as opposed to psychotherapy or other treatments.

Lisa Shin, a psychologist at Tufts University who studies PTSD, agrees.

"So far, no functional neuroimaging measure has been shown to assist in the diagnosis of PTSD," she said. "But this would be a great task to use to test patients."

Source: Seed Magazine