title: Absence of face-specific cortical activity in the complete absence of awareness: converging evidence from functional magnetic resonance imaging and event-related potentials.
abstract: In this study, we explored the neural correlates of perceptual awareness during a masked face detection task. To assess awareness more precisely than in previous studies, participants employed a 4-point scale to rate subjective visibility. An event-related fMRI and a high-density ERP study were carried out. Imaging data showed that conscious face detection was linked to activation of fusiform and occipital face areas. Frontal and parietal regions, including the pre-SMA, inferior frontal sulcus, anterior insula/frontal operculum, and intraparietal sulcus, also responded strongly when faces were consciously perceived. In contrast, no brain area showed face-selective activity when participants reported no impression of a face. ERP results showed that conscious face detection was associated with enhanced N170 and also with the presence of a second negativity around 300 msec and a slow positivity around 415 msec. Again, face-related activity was absent when faces were not consciously perceived. We suggest that, under conditions of backward masking, ventral stream and fronto-parietal regions show similar, strong links of face-related activity to conscious perception and stress the importance of a detailed assessment of awareness to examine activity related to unseen stimulus events.
authors.affiliation: Cuban Neuroscience Center, Havana 10400, Cuba. valia.rodriguez@gmail.com
authors.forename: Valia
authors.initials: V
authors.lastname: Rodríguez
authors.forename: Russell
authors.initials: R
authors.lastname: Thompson
authors.forename: Mark
authors.initials: M
authors.lastname: Stokes
authors.forename: Matthew
authors.initials: M
authors.lastname: Brett
authors.forename: Indira
authors.initials: I
authors.lastname: Alvarez
authors.forename: Mitchell
authors.initials: M
authors.lastname: Valdes-Sosa
authors.forename: John
authors.initials: J
authors.lastname: Duncan
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology; D001364:Awareness / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005145:Face; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010470:Perceptual Masking / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*