Unconscious presentation of fearful face modulates electrophysiological responses to emotional prosody.

Cross-modal integration of visual and auditory emotional cues is supposed to be advantageous in the accurate recognition of emotional signals. However, the neural locus of cross-modal integration between affective prosody and unconsciously presented facial expression in the neurologically intact population is still elusive at this point. The present study examined the influences of unconsciously presented facial expressions on the event-related potentials (ERPs) in emotional prosody recognition. In the experiment, fearful, happy, and neutral faces were presented without awareness by continuous flash suppression simultaneously with voices containing laughter and a fearful shout. The conventional peak analysis revealed that the ERPs were modulated interactively by emotional prosody and facial expression at multiple latency ranges, indicating that audio-visual integration of emotional signals takes place automatically without conscious awareness. In addition, the global field power during the late-latency range was larger for shout than for laughter only when a fearful face was presented unconsciously. The neural locus of this effect was localized to the left posterior fusiform gyrus, giving support to the view that the cortical region, traditionally considered to be unisensory region for visual processing, functions as the locus of audiovisual integration of emotional signals.