Objectives: To investigate the developmental trajectory of neural systems associated with face processing.
Methods: 8 male individuals with autism and 8 typically developing male subjects participated in this study. Participants were matched on age (mean 12 years) and IQ. All measurements were taken at the Brain Research Unit, Helsinki University of Technology, using a VectorView(TM) system providing first-order gradiometers most sensitive to directly underlying neuronal currents. The participants performed a matching task that required attention to be paid to the face, where pairs of images of adolescents and motorbikes were presented sequentially. These brain data were compared to data measured with the same scanner in the same individuals who had performed the same task 3 years earlier. All participants and their parents gave informed consent (Helsinki Declaration) before experimentation.
Results: In both subject groups, by the age of 12, very early (< 60 ms) neural responses to faces exhibit amplitudes similar to those observed in adults. Adult-like signal topographies, however, are only observed in typically developing subjects at early latency. At 100 ms, responses to motorbikes (age 9) and to face and motorbike images (age 12) are observed over right inferior occipito-temporal regions in individuals with autism but not in typically developing subjects.
Conclusions: The development of neural systems associated with face processing has not reached adult level by early adolescence in autism. In particular, neural responses at very early latency that have received little attention previously may hold vital clues to understand atypical development.