THURSDAY, May 24 (HealthDay News) -- Exposure therapy is linked with reduced phobogenic image-induced activity in a network of brain regions, and the reduced responsiveness persists for six months, according to a study published online May 23 in the Proceedings of the National Academy of Sciences.

Noting that a single session of exposure therapy can eliminate fear of phobogenic objects, Katherina K. Hauner, Ph.D., from the Northwestern University Feinberg School of Medicine in Chicago, and colleagues investigated the neural mechanisms of this outcome. Changes in brain activity were monitored after a successful two-hour treatment.

The researchers found that, before therapy, compared with neutral images, phobogenic images induced activity in a network of regions (including the amygdala, insula, and cingulate cortex). Responsiveness of this fear-sensitive network was attenuated by successful therapy, which simultaneously increased prefrontal involvement. The attenuation of the fear network activity persisted at six months, but not the prefrontal involvement. Individual differences in the magnitude of visual cortex activations, which were recorded soon after therapy, predicted the outcome of therapy at six months.

"Successful therapy thus entailed stable reorganization of neural responses to initially feared stimuli," the authors write. "These effects were linked to fear-extinction mechanisms identified in animal models, thus opening new opportunities for the treatment and prevention of debilitating anxiety disorders."

Abstract
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