Aim 1. Study pathophysiology of recent-onset tics. Aim 1a. Identify clinical, neuropsychological, and brain imaging features that differentiate children with recent tic onset ("New Tics" group) from tic-free controls. We will test a priori hypotheses including tic suppression, inattentiveness, caudate nucleus volume, tic severity, and premonitory urges (see "Summary of hypotheses" on the 3rd page of Research Strategy). Secondary analyses will apply support vector machine (SVM) learning to a rich set of data to discover novel, multivariate differences in the New Tics group [3,45]. These data will also include tic phenomenology, psychiatric diagnosis, habit learning, motor dexterity, structural MRI, perfusion MRI, and resting state functional connectivity fMRI (rs-fcMRI).