Early Local Activity in Temporal Areas Reflects Graded Content of Visual Perception.
Frontiers in psychology January 1, 2016 Chiara F Tagliabue, Chiara Mazzi, Chiara Bagattini et al. 69 citations
Visual conscious experience is graded rather than all-or-none, and its neural signature appears in early local brain activity without requiring later frontal involvement. Using electroencephalography, researchers recorded event-related potentials while participants viewed low-contrast visual stimuli and rated their perceptual clarity on a four-point scale. A left centro-parietal negative deflection (Visual Awareness Negativity, VAN) at 280–320 milliseconds reflected the perceptual content, and a bilateral positive deflection (Late Positivity, LP) at 510–550 milliseconds reflected post-perceptual processes. The amplitude of both deflections increased gradually with reported awareness. Source localization placed the generators of phenomenal content in the left temporal lobe.