Anterior insular activity signals perceptual conflicts induced by temporal and spatial context.

The signals registered by our senses are inherently ambiguous. Subjective experience, by contrast, is informative: it portrays one's interpretation of the sensory environment at a time while discarding competing alternatives. This is exemplified by bistable perception, where ambiguous sensory information induces prolonged intervals of alternating unambiguous perceptual states. According to neurocomputational predictive-processing accounts of bistable perception, perceptual experiences in the recent past constitute a predictive context that stabilizes perception, while sensory information in conflict with this predictive temporal context evokes perceptual prediction errors. These perceptual prediction errors are thought to drive spontaneous perceptual switches. In this study, we compared neural correlates of perceptual conflicts induced by violations of temporal context to conflicts induced by spatial context. To this aim, we used functional magnetic resonance imaging and a bistable perception paradigm with temporal and spatial context modulation. Twenty-six healthy participants viewed intermittent presentations of ambiguous structure-from-motion stimuli either in isolation (conflict with temporal context) or embedded in a similar but unambiguous surround stimulus (conflict with spatial context). Only the anterior insula bilaterally showed brain activation associated with both types of perceptual conflict. Approximate perceptual prediction errors derived from generalized linear mixed-effects models yielded signals in the anterior insula bilaterally, the right inferior frontal gyrus, and the right inferior parietal lobe. Together, these findings point to a key role of the anterior insular cortex in detecting perceptual conflicts and thus in the construction of unambiguous perceptual experiences.