Supramodal NCCs of near-threshold perception

The quest for consciousness is one of the most important challenges in cognitive neuroscience. How do conscious experiences about our sensory world arise from brain activity? And is the conscious experience of hearing a sound, seeing a flash or feeling a touch associated with one common core- activity pattern in the brain irrespective of the specific sensory modality (i.e. seeing, hearing, touch)? The research project titled supramodal neural correlates of consciousness of near -threshold perception led by Andreas Wutz at the University of Salzburg has set out to elucidate just that. We use sensory stimuli (i.e. sounds, flashes, vibrations), which are sometimes perceived and other times missed (on about 50% cases, respectively), and aim to identify the brain activity patterns associated with this near-threshold perception for each sensory modality. First, we investigate brain activity during auditory and somatosensory perception. Then, we will test whether these putatively supramodal neural patterns are required for conscious perception in the visual domain. The hypothesis is that if brain activity predicting consciousness for hearing and touch reflect supramodal neural correlates of consciousness, then interfering with these processes should disrupt conscious seeing at the perceptual threshold. In two experiments using magneto-encephalography (MEG) and functional magnetic resonance imaging (fMRI) a paradigm will be established with auditory and somatosensory near-threshold perception. Novel analytical sophistication (i.e. Representational Similarity Analysis, RSA) will be employed to assess supramodal neural correlates of consciousness and fuse the fMRI and MEG data to obtain a coherent spatio-temporal description. This information will be used in a decisive study in the visual domain to interfere with relevant cortical nodes at specified times using transcranial magnetic stimulation (TMS). Our previous work (Sanchez et al., PNAS, 2020) strongly suggests supramodal neural correlates of consciousness for near-threshold perception. However, the localization and timing of these effects remain uncertain. Thus, running the same experiments using MEG, fMRI and TMS will provide complementary information, relevant for current consciousness frameworks. Moreover, using MEG and fMRI first in the auditory / somatosensory experiments to guide the final TMS-experiment in the visual domain, is furthermore the conceivably most rigorous approach to probe the functional relevance of the neural patterns in healthy participants. Experienced cognitive neuroscientists will contribute their complementary expertise. The lead-PI, Andreas Wutz, has a strong track record in perception science. The internal collaborators, Nathan Weisz and Martin Kronbichler, are the respective heads of the MEG, MRI and TMS labs. The external collaborator (Radoslaw Cichy) is a leading researcher in applying RSA to M/EEG and fMRI data. A talented PhD student will complement the team.