Modality-specific effects of aversive expectancy in the anterior insula and medial prefrontal cortex

Expectations modulate the subjective experience of pain by increasing sensitivity to nociceptive inputs, an effect mediated by brain regions such as the insula. However, it is still unknown whether the neural structures underlying pain expectancy hold sensory-specific information or, alternatively, code for modality-independent features (eg, unpleasantness), potentially common with other negative experiences. We used functional magnetic resonance imaging to investigate neural activity underlying the expectation of different, but comparably unpleasant, pain and disgust. We presented participants with visual cues predicting either a painful heat or disgusting odor, and assessed how they affected the subsequent subjective experience of stimuli from the same (within-modality) or opposite (cross-modal) modality. We found a reliable influence of expectancy on the subjective experience of stimuli whose modality matched that of the previous cue. At the brain level, this effect was mediated by the intermediate dysgranular section of the insula, whereas it was suppressed by more anterior agranular portions of the same region. Instead, no expectancy modulation was observed when the modality of the cue differed from that of the subsequent stimulus. Our data suggest that the insular cortex encodes prospective aversive events in terms of their modality-specific features, and whether they match with subsequent stimulations.