MULTIMODAL BRAIN NETWORKS: INTEGRATION BY SYNCHRONIZATION
Cognitive processes, including those important in psychophysics, arise from the coordinated activity of multiple brain regions. Such transient functional integration is especially critical in multimodal processing, for example audio-visual speech perception, or cross-modality attention orienting. We describe briefly a general theory of how such functional coupling is implemented by synchronization of the neural activity in the relevant brain areas at specific frequencies, and give examples of empirical work in audio-visual speech perception and cross-modal attention orienting to support the theory. The empirical work emphasizes phase- synchronous gamma-oscillatory networks that are transiently activated either by the perception of audiovisual speech asynchrony or by the orienting of attention in one sensory modality caused by the appearance of a cue in a different sensory modality.