Behavioral, as with all, functions of the brain are governed by biochemical processes in and between brain cells. Neurotransmitters are particularly important in these processes because they are responsible for relaying information between the brain cells. The neurotransmitter dopamine is believed to be directly involved in the neuronal circuitry of pleasure and reward, and hence is an important contributor to behavior. Extensive research into understanding mechanisms involved in dopamine release and regulation may allow us to develop potential pharmacological solutions to eliminate negative behaviors such as drug addiction. Detection of dopamine was performed electrochemically, placing microelectrodes into regions of the brain that were abundant in dopamine release and receptor sites. With a stimulating electrode, artificial action potentials were generated that mimicked biological conditions conducive to dopamine release. The dopamine release was then analyzed under various pharmacological conditions to determine which biological mechanisms were responsible for regulating the amount of dopamine released per stimulation. Additional experiments were performed to determine which other neurotransmitters might be involved in reward mechanisms. A microsensor capable of selectively detecting the neuromodulator nitric oxide was developed to measure changes of nitric oxide in vitro. My thesis has focused primarily on developing detection methods that allow for an understanding of the factors and mechanisms that regulate extracellular concentrations of neurotransmitters.