Graduate student Marc Normandin has presented the fourth summer seminar on Kinetic Modeling of Positron Emission Tomography Data: Probing the Dopamine System. Neurotransmitters are chemical compounds that transmit nerve impulses across synapses (the junction between two nerve cells or neurons). Dopamine is a neurotransmitter that has been implicated in the processing of rewarding stimuli, and the reinforcing effects of drugs and alcohol are believed to be associated with the speed of dopamine release. While reinforcing rewarding stimuli can be a good thing, in the case of alcohol or drugs it could have serious repercussions including triggering substance abuse and dependence.