33

Neuropsychological studies in Autism Spectrum Disorders (ASD) report a dissociation between preserved low-level processing and deficits in high-level processing in various cognitive domains. This pattern suggests a lack of integration of information between posterior brain areas associated with sensory processing, and anterior brain areas, especially frontal, which are specialized in complex processing. The integration of information between different brain areas refers to anatomical connectivity, but also functional and effective connectivity, observed during a given task. The disconnection model in autism provides an explanation of these deficits and proposes a rostro-caudal and inter-hemispheric under-connectivity, generating a deficit in the integration of information by anterior brain areas, while preserved capacities rely on over-connectivity within posterior brain areas. In this review, we present recent brain imaging data that may help to understand behavioral impairments in autism. Anatomical and functional MRI studies suggest that disorders of language and communication are mainly associated with rostro-caudal under-connectivity and behavioral disorders with subcortical over-connectivity. These results are confirmed by another imaging technique, electroencephalography (EEG), and by pathological studies that show the limits of this disconnection model.