Presentation Information
[P2-15]Neural Bases of the Audiovisual Temporal Binding Window Using TMS
*Solène Leblond1, Tutea Atger1, Franck-Emmanuel Roux1,2, Robin Baurès1, Céline Cappe1 (1. CerCo (Centre de Recherche Cerveau et Cognition), CNRS UMR 5549, University Toulouse (France), 2. Pôle neurochirurgie, CHU Purpan, Toulouse (France))
Keywords:
Temporal Binding Window,Multisensory Integration,Transcranial Magnetic Stimulation,AudioVisual
The temporal law, one of the main principles of multisensory integration (Stein & Meredith, 1993) stipulates that two stimuli from two distinct modalities must occur synchronously to be perceived as part of the same event. The temporal binding window (TBW) corresponds to the time interval within which auditory and visual stimuli are perceived as synchronous. Although the brain regions involved in audiovisual TBW have been identified, such as the superior temporal gyrus (STG), prefrontal cortex, and primary sensory areas (Zhou et al., 2020), most studies relied on correlational methods (Vaidya et al., 2019). Zmigrod & Zmigrod (2015) used tDCS to establish a causal link between the right posterior parietal cortex (rPPC) and TBW plasticity.
Our study aims to confirm the involvement of the STG and the intraparietal sulcus (IPS) in TBW using transcranial magnetic stimulation (TMS) guided by anatomical MRI. By applying single-pulse TMS at different time delay after stimulus presentation, we are also able to investigate the temporal dynamics of the neural processes underlying the TBW. Participants performed a simultaneity judgment task in which they were asked to determine whether two stimuli, one visual and one auditory, were synchronous. Single-pulse TMS was applied with six delays ranging from 50 to 300 ms post visual stimulus, over the IPS, STG, or vertex (control site).
Our results showed a temporal dynamics different involvement of the IPS and STG. First, the right STG is involved as early as 100ms. This is followed by the involvement of the left IPS (150 ms) and then a later the one of right and left STG (250 ms).
Our results partially confirm those of Zmigrod and Zmigrod (2015) by showing IPS involvement, though only in the left hemisphere at 150 ms post stimuli. TMS enabled us to reveal the timing of this activation, highlighting the left IPS’s role at this latency. We also confirm the involvement of the STG at both early and later stages of the simultaneity judgment process. Early stimulation of these regions increased the perception of simultaneity, whereas later stimulation, mainly to the STG, increased asynchrony detection. These findings suggest that the IPS and STG belong to a broader cortical network supporting the TBW, with each region contributing at different stages of multisensory processing.
Our study aims to confirm the involvement of the STG and the intraparietal sulcus (IPS) in TBW using transcranial magnetic stimulation (TMS) guided by anatomical MRI. By applying single-pulse TMS at different time delay after stimulus presentation, we are also able to investigate the temporal dynamics of the neural processes underlying the TBW. Participants performed a simultaneity judgment task in which they were asked to determine whether two stimuli, one visual and one auditory, were synchronous. Single-pulse TMS was applied with six delays ranging from 50 to 300 ms post visual stimulus, over the IPS, STG, or vertex (control site).
Our results showed a temporal dynamics different involvement of the IPS and STG. First, the right STG is involved as early as 100ms. This is followed by the involvement of the left IPS (150 ms) and then a later the one of right and left STG (250 ms).
Our results partially confirm those of Zmigrod and Zmigrod (2015) by showing IPS involvement, though only in the left hemisphere at 150 ms post stimuli. TMS enabled us to reveal the timing of this activation, highlighting the left IPS’s role at this latency. We also confirm the involvement of the STG at both early and later stages of the simultaneity judgment process. Early stimulation of these regions increased the perception of simultaneity, whereas later stimulation, mainly to the STG, increased asynchrony detection. These findings suggest that the IPS and STG belong to a broader cortical network supporting the TBW, with each region contributing at different stages of multisensory processing.