Cerebral Bases and Neural Dynamics of Audiovisual Temporal Binding Window: a TMS study

The temporal binding window (TBW) refers to the time interval within which two stimuli, typically visual and auditory, are perceived as synchronous. Neural bases underlying this process consistently implicate a large-scale network with superior temporal sulcus (STS) as a central hub, alongside contributions from primary auditory and visual cortices and higher-order areas including prefrontal and posterior parietal cortex. This study aimed to provide causal evidence for the involvement of superior temporal gyrus (STG) and intraparietal sulcus (IPS) in the simultaneity judgment (SJ) task using MRI-guided transcranial magnetic stimulation (TMS). In particular, we aimed to clarify temporal dynamics of these regions in audiovisual synchrony perception. Forty adults performed an SJ task in which they had to determine whether stimuli were synchronous or asynchronous. Single-pulse TMS was applied over bilateral IPS, STG, or the vertex at different delays following stimulus offset. Early stimulation of left IPS and right STG increased the proportion of "synchronous" responses. In contrast, later stimulation of bilateral STG was associated with reduced synchrony perception. These findings provide causal evidence for a dynamic interplay between parietal and temporal regions in audiovisual temporal integration. Early IPS and STG involvement facilitates temporal integration, while later STG activity promotes perceptual segregation.