Changes in latency of brain rhythms in response to affective information of visual stimuli

It is widely known that emotionally-arousing pictures are perceived more rapidly than non-arousing pictures, although neural underpinnings of this effect remain unclear. Using electroencephalography, we presently measured neural oscillatory rhythms of the human brain in response to various emotional images from the International Affective Picture System. We found that an oscillation frequency in the alpha-to-beta band (8-30 Hz) became higher over the parietal cortex when participants viewed emotionally-arousing than non-arousing pictures. This modulation of neural rhythms was also observed in a valence dimension; emotionally-negative pictures induced faster neural rhythm than emotionally-positive pictures. Those results were consistent with previous studies reporting a speeded perception of high-arousing and negative stimuli (e.g. snakes and spiders) and further provided neural evidence for an adaptive function of emotion to accelerate the processing of potentially-dangerous stimuli.