When coupled with a microelectrode, background-subtracted fast scan cyclic voltammetry (FSCV) allows fast, sensitive and selective determination of analytes within a small spatial location. For the past 30 years experiments using this technique have been largely confined to recordings at a single microelectrode. Arrays with closely separated microelectrodes would allow researchers to gain more informative data as well as probe regions in close spatial proximity. This work presents one of the first FSCV microelectrode arrays (MEA) implemented in vivo with the ability to sample from different regions in close spatial proximity (equidistant within 1 mm). The array is manufactured from fused silica capillaries and a microfabricated electrode spacer. The functionality of the array is assessed by simultaneously monitoring electrically stimulated dopamine (DA) release in the striatum of anesthetized rat. As expected, heterogeneous dopamine release was simultaneously observed. Additionally, the pharmacological effect of raclopride (D2 receptor antagonist) and cocaine (monoamine uptake blocker) on the heterogeneity of DA release, in spatially different brain regions was shown to alter neurotransmitter release at all four electrode sites
