Neurobiology and Functional Anatomy of Tic Disorders

Abstract

Abstract This chapter summarizes the highly valuable contribution of magnetic resonance imaging (MRI) to the understanding of the functional anatomy of tics and related disorders. Structural MRI studies have revealed altered striatal volumes in children and adults with Tourette syndrome (TS), although results are inconsistent. Cortical thinning in sensorimotor regions has been detected in children and adults with TS, with correspondence between cortical region and types of tics. Whereas adults with TS show cortical thinning and reduced gray matter volume in prefrontal regions, suggesting a failure in neural compensation to control tics into adulthood, results from children with TS are mixed. Functional MRI (fMRI) studies examining tic-related activity suggest that the supplementary motor area is involved in the premonitory urge, whereas fMRI studies examining motor and cognitive control in TS report inconsistent findings. Functional connectivity MRI studies suggest complex differences in brain networks. This chapter discusses limitations of the existing studies and future directions, including the necessity to mitigate motion artifacts because they can cause systematic alterations in MRI measures.