Beyond primary visual cortex: The leading role of lateral occipital complex in early conscious visual processing

• Published in: NeuroImage (Orlando, Fla.) Fla.), 2024-09, Vol.298, p.120805, Article 120805
• Main Authors: Colombari, Elisabetta, Parisi, Giorgia, Tafuro, Alessandra, Mele, Sonia, Mazzi, Chiara, Savazzi, Silvia
• Format: Article
• Language: English
• Subjects: Adult; Awareness - physiology; Brain; Brain Mapping; Consciousness; Consciousness - physiology; EEG; Electroencephalography; EROS; Event-related potentials; Event-related potentials (ERP); Evoked Potentials, Visual - physiology; Experiments; Fast optical imaging; Female; Humans; Information processing; Male; Neuroimaging; Occipital lobe; Occipital Lobe - diagnostic imaging; Occipital Lobe - physiology; Primary Visual Cortex - diagnostic imaging; Primary Visual Cortex - physiology; Sensorimotor integration; Standard deviation; Temporal lobe; Vision; Visual awareness; Visual awareness negativity (VAN); Visual cortex; Visual Cortex - diagnostic imaging; Visual Cortex - physiology; Visual perception; Visual Perception - physiology; Visual stimuli; Young Adult
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2024.120805

•Fast Optical Imaging allows to unveil spatio-temporal dynamics of consciousness•When entering consciousness, visual stimuli elicit a sustained activation of LOC•LOC activity predicts subsequent activity in visual and motor areas•Activity in LOC occurs in the temporal window of VAN•LOC could represent a reliable neural correlate of phenomenal consciousness The study of the neural substrates that serve conscious vision is one of the unsolved questions of cognitive neuroscience. So far, consciousness literature has endeavoured to disentangle which brain areas and in what order are involved in giving rise to visual awareness, but the problem of consciousness still remains unsolved. Availing of two different but complementary sources of data (i.e., Fast Optical Imaging and EEG), we sought to unravel the neural dynamics responsible for the emergence of a conscious visual experience. Our results revealed that conscious vision is characterized by a significant increase of activation in extra-striate visual areas, specifically in the Lateral Occipital Complex (LOC), and that, more interestingly, such activity occurred in the temporal window of the ERP component commonly thought to represent the electrophysiological signature of visual awareness, i.e., the Visual Awareness Negativity (VAN). Furthermore, Granger causality analysis, performed to further investigate the flow of activity occurring in the investigated areas, unveiled that neural processes relating to conscious perception mainly originated in LOC and subsequently spread towards visual and motor areas. In general, the results of the present study seem to advocate for an early contribution of LOC in conscious vision, thus suggesting that it could represent a reliable neural correlate of visual awareness. Conversely, striate visual areas, showing awareness-related activity only in later stages of stimulus processing, could be part of the cascade of neural events following awareness emergence.