Early beta oscillations in multisensory association areas underlie crossmodal performance enhancement

The combination of signals from different sensory modalities can enhance perception and facilitate behavioral responses. While previous research described crossmodal influences in a wide range of tasks, it remains unclear how such influences drive performance enhancements. In particular, the neural mechanisms underlying performance-relevant crossmodal influences, as well as the latency and spatial profile of such influences are not well understood. Here, we examined data from high-density electroencephalography (N = 30) and electrocorticography (N = 4) recordings to characterize the oscillatory signatures of crossmodal facilitation of response speed, as manifested in the speeding of visual responses by concurrent task-irrelevant auditory information. Using a data-driven analysis approach, we found that individual gains in response speed correlated with reduced beta power (13-25 Hz) in the audiovisual compared with the visual condition, starting within 80 ms after stimulus onset in multisensory association and secondary visual areas. In addition, the electrocorticography data revealed a beta power suppression in audiovisual compared with visual trials in the superior temporal gyrus (STG). Our data suggest that the crossmodal facilitation of response speed is associated with early beta power in multisensory association and secondary visual areas, presumably reflecting the enhancement of early sensory processing through selective attention. This finding furthers our understanding of the neural correlates underlying crossmodal response speed facilitation and highlights the critical role of beta oscillations in mediating behaviorally relevant audiovisual processing. Significance Statement The use of complementary information across multiple senses can enhance perception. Previous research established a central role of neuronal oscillations in multisensory perception, but it remains poorly understood how they relate to multisensory performance enhancement. To address this question, we recorded electrophysiological signals from scalp and intracranial electrodes (implanted for presurgical monitoring) in response to simple visual and audiovisual stimuli. We then associated the difference in oscillatory power between the two conditions with the speeding of responses in the audiovisual trials. We demonstrate, that the crossmodal facilitation of response speed is associated with beta power in multisensory association areas during early stages of sensory processing. This finding highlights the importance of beta oscillations in mediating behaviorally relevant audiovisual processing. ### Competing Interest Statement The authors have declared no competing interest.