Fusiform gyrus responses to neutral and emotional faces in children with autism spectrum disorders: a high density ERP study.

Face processing is a neural mechanism that allows understanding social information and cues conveyed by faces, whose dysfunction has been postulated to underlie some of the behavioral impairments characterizing autism spectrum disorders (ASD). A special region of the cortex, the fusiform gyrus (FG), is believed to be the specific area for processing face features and emotions. However, behavioral, fMRI and ERP studies addressed to investigate the role of FG dysfunction in ASD have led to conflicting results. Using a high-density EEG system, we recorded the face-sensitive ERP to neutral and emotional (happiness and fearful) faces, as a measure of early activity of the FG, in children with high functioning ASD. By controlling a number of experimental and clinical variables that could have biased previous research--such as gaze direction, attention to tasks, stimulus appearance and clinical profiles--we aimed to assess the effective role of the FG in the face emotion processing deficit hypothesized in ASD. No significant differences in early face-sensitive ERP components were found between ASD and neurotypical children. However, a systematic latency delay and amplitude reduction of all early potentials were observed in the ASD group, regardless of the stimulus, although more evident for emotions. Therefore, we can assume a diffuse dysfunction of neural mechanisms and networks in driving and integrating social information conveyed by faces, in particular when emotions are involved, rather than a specific impairment of the FG-related face processing circuit. Nevertheless, there is need of further investigation.