Early functional brain development in autism and the promise of sleep fMRI

Abstract

Functional magnetic resonance imaging (fMRI) is a powerful tool for examining brain function but has yet to be systematically applied to the study of brain development in autism. Recently, however, scientists have begun to apply fMRI during natural sleep as a mechanism to study function in the developing brain. When considering the study of autism, this method opens considerable doors because it eliminates biases of past studies which only sampled from high-functioning, older populations. This paper describes the application of sleep fMRI as a way to study both extrinsic and intrinsic brain functions in autism between 12 and 36 months. Preliminary studies that use sleep fMRI method show that defects in the superior temporal gyrus (STG) in response to language are early emerging in autism and can be found in as young as 14 months in age. As such indices of abnormal early development of the STG may prove useful in the search for a biomarker of autism detectable during the infancy period. From a theoretical standpoint, examining sleep fMRI studies in autism gains some clarity when placed in context of the more established literature on structural brain development of autism which suggests that autism involves early brain overgrowth. Studies of plasticity in autism have yet to be done, but it is likely that the window of opportunity for altering the course of brain development in autism begins within the first year of life. The ability to do so relies on improving and streamlining early identification and thus early treatment efforts.