Temporal coincidence is a crucial feature for audiovisual (AV) integration, and recent neurophysiological findings provide evidence for the role of oscillations in the temporal binding of information. Specifically, low-frequency oscillatory phase alignment between visual and auditory cortices has been proposed to support AV integration in time (Lakatos et al., 2008; Schroeder & Lakatos, 2009). Here we hypothesized that if phase coincidence was critical for perceiving synchrony between auditory and visual events, shifts in the phase should be commensurate with the subjective perception of AV events. To test this, participants underwent AV temporal recalibration (Fujisaki et al., 2004) while being recorded with magnetoencephalography (MEG). Temporal recalibration consisted in adapting subjects to desynchronized AV events in order to induce perceptual shifts of AV temporal order. Each recalibration period was followed by an assessment of participant’s temporal order threshold. Stimuli during recalibration were presented at an average rate of 1Hz leading to a prominent tagging in both auditory and visual cortices. Analyses were carried out in source space (dSPM, cortically constrained source orientations) and restricted to sensory cortices. We show that the variability in perceived temporal order is captured by non-stationary 1Hz entrainment: the preferential phase at this frequency was significantly shifted between the beginning and the end of the recalibration period in sensory cortices. Individuals’ perceived simultaneity could be accounted for by systematic shifts in the phase of auditory but not visual neural responses. All together, our results provide a novel physiological index for subjective simultaneity suggesting that auditory cortex recalibrates its timing to the visual spatial anchor.

Temporal order; perception; oscillatory entrainment; multisensory; MEG; simultaneity; delta band