Fig. 3.

Differences in prestimulus neural activity before pain and no pain trials. (Left) Brain areas in which signals detected in a 3-sec prestimulus period were greater before pain trials than before no pain trials. (Right) Reverse contrast. Activations are reported at a statistical threshold of P < 0.001, uncorrected, except for a priori hypothesized regions, which were thresholded at P < 0.005, uncorrected (see Materials and Methods). For visualization, prestimulus activations are shown at a threshold of P < 0.05 uncorrected. aINS, anterior insular cortex (coordinates −40, 20, 2; z = 2.6); PAG (coordinates 4, −26, −8 and − 6, −24, −8; z = 2.6).