Differential Cortical Activation During Perceptual Reversals in Emotional Binocular Rivalry: Insights into Bistable Perception from EEG and Computational Modelling

Navdeep AhujaRatna Sharma^*

• All India Institute of Medical Sciences, New Delhi, New Delhi, India

Perceptual reversals in the bistable stimuli have served as an intriguing phenomenon to investigate the brain's perceptual processes. Although low-level inhibitory and oscillatory activity in neural assemblies was considered a potential mechanism, recent evidence also points to the significant role of higher-level right frontoparietal networks in the perceptual reversals with some commonalities and differences across different studies. The present study investigates the role of emotional stimuli for the recruitment of these higher-level areas. Activation of different neural networks was studied during the perceptual reversals in the binocular rivalry of emotional stimuli across different categories differing in emotional valence presented with an intermittent paradigm. Three pairs of stimuli including negative vs neutral valence, positive vs neutral valence and negative vs positive valence were studied. Using IAPS images and a 128-channel EEG with sLORETA source localisation, we found that the pair of negative vs neutral stimuli elicited pre-and post-stimulus activations in right frontoparietal and occipital regions from -100 to 100 ms, along with significant left hemispheric activation, all of which sharply reduced 100 to 600 ms after the reversals. In contrast, the positive stimuli paired with either neutral or negative stimuli did not elicit such activations, although a consistent pattern of sharp reduction in activity was observed across all categories. Additionally, we performed a novel computational modelling based on predictive coding, including the role of prediction errors in the perceptual processes, with a novel step of adding the differential cortical processing based on varying stimulus parameters and fitting according to the empirical results obtained in the study. Together, these findings offer new insights into the active inferential processes of the bistable perception and account for the differential cortical activation across the categories of stimuli.