The goal of this project is to examine dysfunction of preattentive and attentive regulatory mechanisms in children and infants who exhibit disturbance in the modulation of cognitive, affective, and social processes. Actions of these regulatory mechanisms are assessed through examination of steady-state autonomic and central nervous system activity and of the response of these systems to environmental events. Measurement of the blink reflex, heart rate, respiration, and task performance during rest and in response to simple two-stimulus paradigms permit assessment of the integration of different neural systems (sensory, motor and autonomic), preattentive inhibitory and excitatory effects on sensory processing, and different components of attention including intensity, maintenance, breadth (focus or selectivity), and resistance to distraction. In the first year of this project, laboratory and computer facilities have been developed for stimulus presentation as well as data acquisition and analysis. Groups of normal infants and children were tested to examine developmental patterns in regulation. A study comparing differences in regulatory function in groups of 6- to 11-year-old children with behavioral patterns of attentive dysfunction is underway. These groups include children with Attention-deficit Hyperactivity Disorder (ADHD), with Tourette's Disorder (TD), and with both ADHD and TD.