In his proposed experimental plan, Dr. Faull intends to use the techniques of in vivo voltammetry and intracerebral microdialysis to test three specific hypotheses concerning biogenic amine and neuropetide release phenomena. These hypotheses concern the proposed interactions between dopamine, cholecystokinin and neurotensin in mesocorticolimibic and basal ganglia brain regions, and the proposed interactions between dopamine and acetylcholine in the nigrostriatal pathway. The in vivo techniques will be used in conjunction with microbore high- performance liquid chromatography coupled to electrochemical detection and combined gas chromatography/mass spectrometry for quantification of biogenic amines and their metabolites, and radioimmunoassay for quantification of the neuropeptides. By using sophisticated analytical and radioimmunochemical techniques, the proposal of the newly developed in vivo techniques will be extended to important areas of the behavioral and neural sciences and could have a significant impact on understanding of the integration of neurotransmitter release in specific brain areas.