Y: Large-scale neural synchrony associated with top-down selective attentional modulation of Necker cube perception

We investigated top-down selective attentional modulation of bistable perception. Sixteen healthy human observers were presented with the Necker cube on a black background. Observers reported perceptual switches between two possible interpretations by pressing one of two keys. Observers were instructed either to passively view the Necker cube or to try to attend to one of the two possible interpretations. Observers showed strong selective attentional modulation of dominance durations. We measured brain electrical activity by 62ch EEG and used phase locking value to evaluate large-scale phase synchrony between pairs of EEG signals. We observed stronger long-lasting large-scale synchrony at 3-4 Hz among the frontal, parietal and occipital areas associated with perceptual switches in the attentional control condition than in the passive view condition. These results suggest that top-down selective attentional modulation of Necker cube perception is mediated by frontal-parietal-occipital synchrony networks in the theta frequency range. Large-scale neural synchrony is proposed as a mechanism for perceptual binding and functional integration of neural assemblies across brain regions (Varela et al., 2001, Ward