Early and late electrophysiological correlates of gradual perceptual awareness in- and outside the Attentional Blink window

There is an ongoing debate on the neural correlates of consciousness (NCC) in the attentional blink (AB). Theoretical accounts propose that NCC during the attentional blink occur late in the processing hierarchy and that this quality is specific to the AB. We investigated this question by recording event-related potentials during an AB experiment with faces as T2. We analyzed ERPs to T2 stimuli inside (short lag) and outside (long lag) the AB window after carefully calibrating T2 stimuli to ensure equal visibility ratings across lags. We found that the N170, the visual awareness negativity (VAN), and the P3b showed an increased amplitude for seen compared to unseen face stimuli regardless of stimulus lag and that all these components scale linearly with subjective visibility. These findings suggest similar early and late mechanisms of graded perceptual awareness within and outside the AB across perceptual (N170, VAN) and post-perceptual (P3b) processing stages

Differential effects of prediction error and adaptation along the auditory cortical hierarchy during deviance processing

Neural mismatch responses have been proposed to rely on different mechanisms, including prediction error-related activity and adaptation to frequent stimuli. However, the hierarchical cortical structure of these mechanisms is unknown. To investigate this question, we recorded hemodynamic responses while participants (N = 54) listened to an auditory oddball sequence as well as a suited control condition. In addition to effects in sensory processing areas (Heschl's gyrus, superior temporal gyrus (STG)), we found several distinct clusters that indexed deviance processing in frontal and parietal regions (anterior cingulate cortex/supplementary motor area (ACC/SMA), inferior parietal lobule (IPL), anterior insula (AI), inferior frontal junction (IFJ)). Comparing responses to the control stimulus with the deviant and standard enabled us to delineate the contributions of prediction error- or adaptation-related brain activation, respectively. We observed significant effects of adaptation in Heschl's gyrus, STG and ACC/SMA, while prediction error-related activity was observed in STG, IPL, AI and IFJ. Additional dynamic causal modeling confirmed the superiority of a hierarchical processing structure compared to a flat structure. Thus, we found that while prediction-error related processes increased with the hierarchical level of the brain area, adaptation declined. This suggests that the relative contribution of different mechanisms in deviance processing varies across the cortical hierarchy