This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study will use functional MR brain imaging (fMRI) to understand better the neurobiology of neuropsychiatric disorders such as Tourette's syndrome, Obsessive-Compulsive Disorder (OCD), Attention Deficit Hyperactivity Disorder (ADHD), anxiety disorders, substance use disorders, pathological gambling, affective illness and disruptive behavior disorders. Clinical experience has shown that people with a serious neuropsychiatric disorder suffer most not from their primary diagnostic symptoms, but from their difficulties with impulse control, hyperactivity, inattention, and response inhibition. These problems cut across most diagnostic domains and are amongst the most frequent causes for clinical referral. By understanding the neural dysfunction involved in these disorders, we will be better able to design and assess the effects of new therapeutics.