Electrophysiological correlates of consciousness in bimodal (audiovisual) condition

Abstract

The neurobiology underlying consciousness remains poorly understood. As a result, several postulations have been made regarding consciousness and the cognitive processes involved. Electroencephalography (EEG) is a useful tool for studying consciousness and has been pivotal in our understanding of conscious perception. Visual awareness negativity (VAN), auditory awareness negativity (AAN), and late positivity (LP) are all electrophysiological correlates identified and associated with the neural correlates of consciousness using EEG. Converging evidence points to an occipitotemporal origin for the VAN, multiple cerebral regions such as frontal, parietal, cingulate, limbic, and hippocampal for the LP source, and the auditory cortices origin for AAN. The AAN and VAN are documented as the onset of consciousness in auditory and visual modalities, respectively. However, bimodal perceptual awareness and cognitive processing remain understudied. Due to the multisensory integration, it is unknown whether the correlates of consciousness and cognitive mechanisms stay the same as in the single modalities or differ in essence, timing, distribution, or function. In the present study, electrophysiological activity was recorded using EEG while subjects saw and listened to stimuli presented at their awareness threshold using PsychoPy. The preliminary results indicate that neural correlates of conscious perception in bimodal perception are consistent with earlier NCC findings in modality-specific trials of previous studies. However, there are marked differences in NCC and spatial distribution when response requirements are involved in the bimodal trials.