The dynamic role of alpha-band brain oscillations during audiovisual integration of natural scenes

Abstract

The brain is constantly inundated with a stream of input from different sensory modalities. Multimodal information has to be integrated or segregated depending on attentional demands and stimulus properties. How does the brain's information flow adapt to these different require­ment? We used magnetoencephalography (MEG) to investigate the role of alpha synchroniza­tion in complex audiovisual integrationjsegregation of naturalistic stimuli. Participants were asked to watch audiovisual clips while paying attention to either the visual or the auditory modality. The clips mainly contained speech scenes and the auditory part was either congruent or incongruent with the video. We found significant parieto-occipital alpha power suppression when visual attention was compared with auditory attention. Furthermore, incongruent con­ditions were characterized by lateralized alpha synchronization of the right hemisphere when vision was the distractor modality. Finally we observed that alpha oscillations did not disap­pear, even during attentive audiovisual stimulation, suggesting that the alpha cycle may play a role in sensory information processing.