Discrimination of emotional prosodies in human neonates: A pilot fNIRS study

Very early in development, vocal emotional cues are more critical than facial expressions in guiding infants' behavior. However, the processing of emotional prosody in the very early days of life is still far from clearly understood. To address the issue, this study used functional near-infrared spectroscopy to examine brain response of neonates when they passively listened to fearful, angry, happy and neutral prosodies. It was found that while the right temporal cortex (mainly located in the middle temporal gyrus and superior temporal gyrus) exhibited enhanced response to emotional, relative to neutral, prosody, a right parietal area (approximately located in the supramarginal gyrus) showed a heightened sensitivity to fearful, relative to happy and neutral, prosody. These findings highlight the crucial importance of the right hemisphere in the perception of emotional prosody in neonates. Furthermore, the result is consistent with the notion of a negativity bias, supporting the evolutionary importance of threatening information that could be processed at birth.