Neuroimaging in the developmental disorders: the state of the science.

The developmental disorders of childhood autistic, developmental language, reading (dyslexia), and attention deficit-hyperactivity disorders-manifest with deficits in the traditional behavioral domains of cognition, language, visual-spatial function, attention, and socialization. However, none of these disorders has been associated with characteristic discrete focal lesions or recognized encephaloclastic processes. Developmental cognitive neuroscientists must therefore begin with the spectrum of sometimes divergent behaviors occurring within these disorders and work backward in an attempt to identify the responsible anomalous neural systems. Since the advent of "brain imaging" two decades ago, much effort has focused on identifying brain-behavior correlates in these disorders. The results of these neuropathologic, structural, and functional neuroimaging studies are presented and the reasons for the often divergent findings are discussed. As we approach the end of the Decade of the Brain, current neuroimaging techniques give us the technology for the first time to apply a fundamental cognitive approach to brain-behavior relationships in the developmental disorders, to eliminate the conglomeration of "apples and camels" phenomenon. Researchers are working together to create comparable protocols and to adhere to methods that can be replicated across sites. The future prospects for a greater understanding of the developmental disorders are now much brighter with neuroimaging technology.