Biophysical mechanisms to relate large-scale brain network dynamics to individual-specific variability of perception

Perception necessitates interaction amongst neuronal ensembles, the dynamics of which can be conceptualized as the emergent behavior of coupled dynamical systems. Likewise, the variability in perception can be explained to emerge from the modulation of interactions within the underlying neural dynamical system. Employing this framework, we explain the inter-individual variability in McGurk effect – wherein illusory sound is perceived when presented with certain semantically-incongruent audio-visual (AV) syllables. We computed global coherence to capture the cortical dynamics in the electroencephalogram (EEG) signals while the participants with varying McGurk susceptibility perceived congruent and incongruent McGurk-AV syllables. We observed that McGurk susceptibility was negatively correlated to participants’ alpha band global coherence. Our neurobiologically-realistic dynamical model attributed the decrease in alpha band coherence to extremely weak direct auditory(A)-visual(V) coupling that were then validated by source connectivity analysis among constituent cortical generators of neural activity. Overall, we provide a link between functional metrics and underlying neurophysiological mechanisms.