Not alpha power: prestimulus beta power predicts the magnitude of individual temporal order bias for audiovisual stimuli

Individuals exhibit significant variations in audiovisual temporal order perception. Previous studies have investigated the neural mechanisms underlying these individual differences by analyzing ongoing neural oscillations using stimuli specific to each participant. This study explored whether these effects could extend to different paradigms with the same stimuli across subjects in each paradigm. The two human participants groups performed a temporal order judgment (TOJ) task in two experimental paradigms while recording EEG. One is the beep-flash paradigm, while the other is the stream-bounce paradigm. We focused on the correlation between individual temporal order bias (i.e., point of subjective simultaneity (PSS)) and spontaneous neural oscillations. In addition, we also explored whether the frontal cortex could modulate the correlation through a simple mediation model. We found that the beta band power in the auditory cortex could negatively predict the individuals PSS in the beep-flash paradigm. Similarly, the same effects were observed in the visual cortex during the stream-bounce paradigm. Furthermore, the frontal cortex could influence the power in the sensory cortex and further shape the individuals PSS. These results suggested that the individuals PSS was modulated by auditory or visual cortical excitability depending on the experimental stimuli. The frontal cortex could shape the relation between sensory cortical excitability and the individuals PSS in a top-down manner. In conclusion, our findings indicated that the prefrontal cortex could effectively regulate an individuals temporal order bias, providing insights into audiovisual temporal order perception mechanisms and potential interventions for modulating temporal perception.