Early intervention and brain plasticity in autism.

Autism is associated with impairments in brain systems that come on line very early in life. One such system supports the development of face processing. Dawson and colleagues found that 3 year old children with autism failed to show differential event-related potentials (ERPs) to photographs of their mother's versus a stranger's face. Since differential ERP activity to familiar and unfamiliar faces is typically present by 6 months, this represents early brain dysfunction. McPartland and colleagues found that the face-specific ERP component ('N170') is atypical in older individuals with autism. N170 is typically larger to faces than non-faces, and prominent over the right hemisphere. In individuals with autism, N170 was larger for furniture than faces and bilaterally distributed. Biology and experience contribute to the development of face-processing systems. Newborns are capable of recognizing faces. Early face recognition abilities are thought to be served by a subcortical system, which is replaced by an experience-dependent cortical system. Development of a neural system specialized for faces may depend on experience with faces during an early sensitive period. Because children with autism fail to attend to faces, they might not acquire the expertise needed for a specialized face processing system to develop normally. Early interventions that enhance social attention should result in changes in brain activity, as reflected in ERPs to face stimuli, with those children showing the greatest social improvement exhibiting more normal brain activity.