Predicting Response to McGurk Effect Based on Periodic and Aperiodic Prestimulus EEG Activity

Poster Session D - Monday, April 15, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Vinsea A V Singh¹ (vinseasingh@gmail.com), Vinodh G. Kumar^1,2, Arpan Banerjee¹, Dipanjan Roy^1,3; ¹National Brain Research Centre, India, ²Penn State University, ³Indian Institute of Technology (IIT) Jodhpur

Previous studies have reported that prestimulus brain oscillations guide perceptual experiences during audio-visual speech perception. However, 'what' features of these prestimulus power drives multisensory speech perception remains unknown. We explored this question in the context of multisensory integration using EEG recordings of 18 participants previously collected from our group (Kumar et al., 2020) using incongruent McGurk stimuli. We asked whether the subjective differences at the inter-individual and inter-trial levels of variability in prestimulus oscillatory power emerge from the ongoing background (1/f) component of brain activity (or aperiodic activity) or occur due to changes in only the periodic oscillations. Furthermore, we used logistic mixed-effect models to determine the topology of spectral markers that could predict the response to the upcoming illusory perception. We found that perception of the McGurk illusion was predicted by lower occipital alpha (8–12 Hz; Bayes Factor (BF) = 0.51) and lower parietal (BF = 0.48), central (BF = 0.77), and occipital (BF = 0.62) beta (15–30 Hz) oscillations. We also found lower aperiodic offset values over parietal (BF = 0.08) and temporal (BF = 0.16) sensors and a lower ‘global’ effect of exponent over the scalp, which predicted the response to McGurk illusion, suggesting that prestimulus aperiodic exponent contributes globally to the upcoming McGurk percept. In conclusion, our findings suggest that the predominant source of the prestimulus oscillatory state is aperiodic background activity and that variations in these arrhythmic components account for inter-trial and inter-individual variability in perception of the McGurk illusion.

Topic Area: PERCEPTION & ACTION: Multisensory