Visual evoked potentials in humans during recognition of emotional facial expressions

Visual evoked potentials were recorded from the occipital, parietal, central, frontal, and posterior temporal areas of the cortex during recognition of emotionally positive, negative and neutral facial expressions and during passive observation in 22 right-handed healthy subjects. These studies showed that in the posterior temporal areas, the latencies of the N90, P150, and N180 waves of potentials evoked by faces with emotionally negative expressions were significantly shorter than those evoked by other types of facial stimuli. Differences were seen both on recognition and during passive observation. Correct recognition involved both hemispheres and was characterized by high levels of interhemisphere temporal correlation of the processes occurring during the development of the P150 wave in the posterior temporal and the N180 wave in the frontal parts of the cortex. The possible relationship of these data to primary subthreshold recognition of facial expressions in the posterior temporal fields of the cortex is discussed, as is the role of the frontal cortex in completing this process and in taking the correct decision about the nature of the image.