Functional MRI in Autism

Nearly 200 reports of functional MRI (fMRI) studies in autism have been published, including an extensive literature of differential brain activation in autism during cognitive tasks. A selection of reports are reviewed involving brain responses during auditory processing, language, touch perception, visual perception, motor function, oculomotor control, processing of faces, social and empathic reasoning, theory of mind, emotion, attention, executive function, reward processing, and learning. Although the literature is heterogeneous, a trend toward decreased brain activation in complex networks involving unimodal and heteromodal association cortex is apparent. Functions requiring integration of multiple distributed brain regions are particularly affected, and functions such as language that exhibit lateralization of function typically show greater recruitment of contralateral homologous regions in autism. Efforts to establish biomarkers or endophenotypes using fMRI and open questions for further research are discussed.