Auditory-visual multisensory interactions within primary cortices revealed by BOLD peak facilitation
Meuli R, Maeder P, Clarke S, Martuzzi R, Thiran J, Murray M, Michel C
Lausanne University Hospital
Studies in animals have shown multisensory interactions within primary cortices. Here, we provide corresponding, non-invasive evidence in humans, by analyzing the BOLD signal dynamics in response to rudimentary visual, auditory, or simultaneous auditory-visual stimuli during a simple reaction time task. Activation maps show that primary cortices of each sensory modality responded to both visual and auditory stimulation, indicative of multisensory convergence. Peak latencies within primary visual and auditory areas were also statistically compared, and exhibited earlier BOLD responses to multisensory auditory-visual stimuli than either unisensory condition. The implication is that brain areas traditionally considered unisensory contribute to multisensory interactions.