Prediction and perception in the multisensory brain: Supramodal and modality-specific mechanisms of sensory predictions across cortical hierarchies
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To enable sensory perception, the brain evolved a hierarchy of cortices for each sense. A challenge in neuroscience is to characterise commonalities and differences in the representations and mechanisms operating within and controlling neural signalling between cortical hierarchies dedicated to different sensory organs. Here I show that representations supporting cortical responses elicited by sensory prediction violations travelling along the cortical hierarchy are increasingly shared between the senses. To that end, I designed two multisensory variants of the local-global paradigm which violates expectations about sensory inputs at two hierarchical levels: local and global. First, I will demonstrate that the local-global paradigm can dissociate higher-order P3b-like global effects and lower-order MMN-like local effects in the auditory and the somatosensory modality. I will show that cortical representations supporting the global effect are maintained in time in networks shared between the senses. Conversely, cortical activity underpinning the local effect is largely specific to each sensory domain. Building up on my finding that attention enhances ERP signatures of local and global effects across sensory modalities, I will demonstrate that salient deviations are associated with increased connectivity between bilateral inferior frontal gyri in the somatosensory and the auditory domain. Ultimately, I will elucidate the representational and mechanistic basis of cortical responses arising from mismatching sensory modalities. I will provide evidence for the notion that information flow elicited by crossmodal mismatches is ubiquitous between the cortical hierarchies in which the sensory prediction was generated and violated respectively. I will then show that crossmodal mismatches rely on cortical representations which are sustained in time in an early time window consistent with the involvement of networks spanning associative and attention-related cortices. I envision that this research might substantiate the notion of a gradient of supramodality in cortical hierarchies with clinical implications.