Emotion processing in the infant brain: The importance of local information.

Facial expressions provide crucial information for an infant's social and cognitive development. Expressions are discriminated based on specific basic-level information, such as global and local information represented in spatial frequencies. Research in adults suggests that different neural pathways are involved in emotion discrimination, each activated by specific spatial frequency ranges. However, in infants the involvement of spatial frequencies in emotion discrimination is unknown. In the current study we investigated the effect of manipulating spatial frequency information in the face on emotion discrimination. Infants aged 9-10 months (N = 61) viewed happy, fearful, and neutral faces. The faces contained either lower (related to global information) or higher spatial frequencies (related to local information). Brain activity in response to the faces was measured with electroencephalography. Interest was in the effect of emotion and spatial frequency on the amplitude of the N290, P400, and Nc components. Amplitudes of the N290 and P400 components differed between happy versus fearful or neutral faces, although only in the higher, and not the lower, spatial frequency condition. Amplitude of the Nc components differed between happy versus fearful or neutral faces regardless of spatial frequency condition. These results reveal the importance of higher spatial frequencies for emotion discrimination in infants (particularly at the N290 and P400 components). We related these findings to current models on the neural basis of facial-emotion processing.