Cross-regional cortical synchronization during affective image viewing.

Affective perception has been suggested to involve the coordinated activation of widely distributed cortical networks, including those involved in sensory storage/analysis and higher-order structures, such as the prefrontal cortex that regulate these processes. We measured regional electroencephalogram (EEG) activity while young adult participants viewed images varying in arousal and valence (pleasant, neutral, and unpleasant). Viewing highly arousing images led to a significant enhancement of EEG coherence between prefrontal and posterior electrodes in both cerebral hemispheres. Long distance interhemispheric coherence also increased during affective image viewing, but only among females. Increases in coherent brain electrical activity were specific to oscillations in the beta (14 to 30Hz) bandwidth, while right hemispheric networks oscillating in the theta (4 to 7Hz) range tended to de-synchronize during viewing of affective images. Although directionality could not be inferred, analyses of lead-lag relations showed the prefrontal electrodes leading the posterior clusters, consistent with top-down modulation. Our results suggest large-scale synchronization of cortical cells during affective viewing and emphasize the role of beta oscillations in mediating such binding.