Imaging dopamine mediated effects of stress on inhibitory control

You are invited to take part in our research study of the brain, the immune system, and cigarette smoking. We will use brain imaging (PET and MRI) to determine if activation of the immune system leads to greater chance of relapse to smoking. After agreeing to participate in this research, you will receive a low dose of either lipopolysaccharide (LPS) or placebo on scan days and methylphenidate (Ritalin) on PET scan days. There are three PET scans and two MRI scans.