Summary – Neuroanalytial Core The Neuroanalytical Core develops and applies methods to measure electroactive neurotransmitters in vivo. The core will develop and then use electrochemical methods to measure the absolute concentrations of easily oxidized neurotransmitters in vivo – something not possible with other methodology. Fast changes in the extracellular concentration of neurotransmitters can arise from phasic neuronal firing. For this reason, chemical sensors should be able to operate on a wide range of time scales. An ideal sensor for the detection of neurotransmitters has high sensitivity, can distinguish between compounds, and has a fast response time. Electrochemical approaches offer a way to accomplish this for easily oxidized neurotransmitters by using an electrode next to sites where the neurotransmitter is released. The core can monitor rapid, phasic changes using FSCV or slow, tonic changes using FSCAV. Making simultaneous measurements of dopamine and serotonin on multiple timescales has the potential to further understanding of the interactions between the two systems. It is important to note that in vivo experimentation will require informed selection of the brain regions of interest. This instrument allows for the investigation of the interdependence of the dopaminergic and serotonergic systems and the role they play in learning and disease states. Excitingly, this core has been designed to allow additional methods to be incorporated. This core can be used to further behavioral neuroscience and our current understanding of the links between neurochemical systems. We couple the methodologies to neuroscience to ensure that we will continue to advance the impact of the NIDA research community.