Prestimulus Periodic and Aperiodic Neural Activity Shapes McGurk Perception

Area of Science:

• Neuroscience
• Cognitive Science
• Perception Research

Background:

• Prestimulus neural oscillations are known to impact perception.
• The specific features of neural activity driving perception and the role of non-oscillatory activity remain unclear.
• The interaction between periodic and aperiodic neural activity before multisensory stimulus perception is unexplored.

Purpose of the Study:

• To investigate the role of prestimulus periodic power and aperiodic activity in modulating the perception of the McGurk illusion.
• To examine how these neural features influence multisensory perception on a trial-by-trial basis.

Main Methods:

• Human electroencephalography (EEG) study with 18 participants.
• Analysis using logistic mixed-effects models to assess the relationship between neural activity and illusion perception.
• Investigation of alpha, beta, theta, and gamma power, alongside aperiodic offset and exponent values.

Main Results:

• Illusion perception correlated with reduced alpha and beta power, increased theta and gamma power, and lower aperiodic offset and exponent values.
• Aperiodic exponent and periodic power jointly influenced McGurk illusion perception.
• Specific changes in occipital theta, global beta, and occipital/parietal gamma power were associated with altered perception.

Conclusions:

• Aperiodic brain activity is a primary source of variation in prestimulus states.
• Fluctuations in both periodic and aperiodic neural activity contribute to inter-trial variability in McGurk illusion perception.
• Understanding these neural dynamics offers insights into multisensory integration and perceptual decision-making.