Unfolding of lateralized neural responses to facial information
Sanne Brederoo1,2, Berry Van den Berg1,2, Mark Nieuwenstein1, Monicque Lorist1,2; 1Department of Experimental Psychology, University of Groningen, The Netherlands, 2Department of Neuroscience, University Medical Center Groningen, The Netherlands
Face processing has been shown to be more accurate for facial information presented in the left (LVF) than in the right (RVF) visual field. To elucidate neural processes underlying lateralized face processing, we employed a visual EEG-paradigm in which faces could appear as standards or deviant half-faces in the LVF or RVF, while participants performed a task on a centrally presented series of symbols. During LVF-deviant face trials (vs. standards), we observed a negative deflection (~200ms) that was lateralized over right occipital electrodes. Following this initial negativity, both LVF- and RVF-deviants elicited an occipital, broad bilateral negativity compared to standards, starting at ~330ms for LVF-deviants and ~360ms for RVF-deviants. Finally, for both LVF- and RVF-deviants, following this mismatch negativity we observed a decrease in alpha power in the hemisphere contralateral to the visual field in which the deviant half-face appeared, which started earlier for LVF-deviants (~400ms post-stimulus) than for RVF-deviants (~450ms post-stimulus). No LVF/RVF lateralization effects were observed for word stimuli in the same paradigm, indicating that the lateralized processes are face-stimulus-specific. In conclusion, these results suggest that the right cortical regions detect deviances in facial information more rapidly than their left homologues. The timing differences in the observed changes in alpha power, reflecting an increase in cortical activity over the side that processed the deviant (i.e., changing) facial information, suggest a faster recruitment of cortical regions that are relevant to the processing of the deviant face information for the LVF-deviant compared to RVF-deviant.
Topic Area: PERCEPTION & ACTION: Vision