Functional parcellation of the operculo-insular cortex in perceptual decision making: an fMRI study

A current challenge in cognitive neuroscience is to provide an explicit separation of the neural correlates of abstract global decision variables from sensory and integrative ones. In particular, the insular cortex and the adjacent frontal operculum seem to have a crucial but still unclear role in evidence accumulation and decision signaling in perceptual decision-making tasks. Here, we have used a visual decision-making paradigm based on the detection of ambiguous two-tone (Mooney) face stimuli to assess the emergence of holistic percepts. These are constructed using global gestalt rules and not by gradual spatiotemporal increases in sensory evidence. Our paradigm (neurochronometric approach) enabled the experimental separation between multiple cognitive components in perceptual decision validated by both model-driven and data-driven analysis. This strategy allowed for the functional dissection of operculo-insular networks into task related complexes such as anterior (accumulator), middle (decision) and posterior (somatosensory/sensorimotor). We conclude that global perceptual integration based on holistic rules requires a distributed operculo-insular network.