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Abstract:
Introduction:
The anterior insula (AI) has been implicated in the neural encoding of a variety of cognitive and affective states, including the processing of painful, disgusting and unfair events. Evidence also suggests that this applies to events directed to oneself and when observing others exposed to these experiences. The present study aimed to investigate whether the overlap of relevant brain responses in the AI reflects domain-specific coding or a shared neural code for unpleasantness that is common to painful, disgusting and unfair economic experiences.
Methods:
To address this question, we employed multivariate pattern analyses (MVPA) techniques that have previously been used to assess similarity between neural representations across experimental conditions. Using fMRI, we measured brain responses of 19 healthy participants while they performed 3 independent tasks. In each task, we presented aversive or neutral stimuli that were directed either to the participant or a confederate (resulting in a 2 [unpleasantness: aversive, neutral] x 2 [target: self, other] factorial design for each task). Tasks included a pain paradigm (noxious vs. non-noxious electrical stimulations), a taste paradigm (disgusting vs. neutral liquids) and an Ultimatum Game (UG) (unfair vs. moderately fair economic offers). Imaging data were analyzed using cross-classification techniques (MVPA) to test whether variance in neural response pattern evoked in the AI in one task was replicated by response patterns in another task and modality.
Results:
In line with previous evidence, we found that self-directed (participant) and vicarious experiences (confederate) elicited common neural signatures in the AI for the domain of pain, disgust and unfair economic offers (cross-target MVPA). Importantly, cross-modal MPVA identified shared response patterns in AI across sensory modalities of painful and disgusting events, but also response patterns specific to these basic sensory modalities. Finally, cross-modal analysis for the UG showed that response patterns elicited by unfair economic offers were similar to neural signatures for painful and disgusting events.
Conclusions:
We found evidence for both domain-specific coding in the AI as well as for shared neural signatures across economic and basic sensory tasks, presumably coding for the unpleasantness of experiences. This finding suggests that the AI may subserve distinct and parallel processes during exposure to aversive events.
