This chapter discusses the numerous conflicting findings produced by a wide variety of functional imaging studies in Tourette's syndrome (TS) performed by different investigators under different experimental protocols over a large number of years. Superficially, the behavioral phenotypes of TS, obsessive-compulsive disorder (OCD), and attention-deficit hyperactivity disorder (ADHD) differ dramatically: one consists of motor and vocal tics. Another consists of obsessions and compulsions, and yet another consists of inattention, hyperactivity, and impulsivity. The phenomenology of TS introduces numerous potential confounds that can seriously impair our ability to interpret adequately the findings from functional imaging studies. The orbitofrontal cortex is interconnected with the anterior cingulate and other limbic structures. The cingulate cortex is a heterogeneous structure that probably is a component in most of the major cortico-striato-thalamo-cortical (CSTC) pathways: the supplementary motor area, orbitofrontal cortex and temporolimbic circuits.