Figure 1.

Main effect of unconditioned responses. Unconditioned stimulus (US) versus negative conditioned stimulus (CS)- offset in subjects with post-traumatic stress disorder (PTSD) and trauma-exposed non-PTSD control (TENC) subjects. Although the US was 'highly annoying' rather than painful, it elicited massive neuronal responses in classic pain regions including the brainstem, the thalamus, the contralateral sensory cortices, the insula and the middle cingulate. Activations are displayed at a threshold of T > 4 on a template magnetic resonance imaging (MRI) scan.