Neural Correlates of Auditory–Visual Stimulus Onset Asynchrony Detection

TLDR

Intersensory temporal synchrony is a ubiquitous sensory attribute critical for binding multisensory inputs, yet little is known about how the brain detects temporal synchrony between multimodal sensory inputs. Using positron emission tomography, the study showed that detecting auditory‑visual stimulus onset asynchrony activates a large‑scale neural network—including insular, posterior parietal, prefrontal, and cerebellar regions—with the most task‑specific activity in the right insula. Interregional covariance analysis revealed significant task‑related functional interactions among the insula, posterior thalamus, and superior colliculus, leading the authors to propose that the insula, via its short‑latency connections with the tectal system, mediates early‑stage temporally defined auditory‑visual interactions underlying phenomena such as the ventriloquist and McGurk effects.

Abstract

Intersensory temporal synchrony is an ubiquitous sensory attribute that has proven to be critical for binding multisensory inputs, sometimes erroneously leading to dramatic perceptual illusions. However, little is known about how the brain detects temporal synchrony between multimodal sensory inputs. We used positron emission tomography to demonstrate that detecting auditory-visual stimulus onset asynchrony activates a large-scale neural network of insular, posterior parietal, prefrontal, and cerebellar areas with the highest and task-specific activity localized to the right insula. Interregional covariance analysis further showed significant task-related functional interactions between the insula, the posterior thalamus, and superior colliculus. Based on these results and the available electrophysiological and anatomical connectivity data in animals, we propose that the insula, via its known short-latency connections with the tectal system, mediates temporally defined auditory-visual interaction at an early stage of cortical processing permitting phenomena such as the ventriloquist and the McGurk illusions.