The Roles of Dopamine

INTRODUCTION Dopamine (DA) is a neuromodulator (see: NEUROMODULATION IN INVERTEBRATE NERVOUS SYSTEMS and SYNAPTIC CURRENTS, NEUROMODULATION AND KINETIC MODELS) that originates from small groups of neurons in the mesencephalon (the ventral tegmental area (A10), the substantia nigra (A9) and A8) and in the diencephalon (area A13, A14 and A15). Dopaminergic projections are in general very diffuse and reach large portions of the brain. The time scales of dopamine actions are diverse from few hundreds of milliseconds to several hours. We will focus here on the mesencephalic dopamine centers because they are the most studied, and because they are thought to be involved in diseases such as Tourette’s syndrome, schizophrenia, Parkinson’s disease, Huntington’s disease, drug addiction or depression (see DISEASE: NEURAL NETWORK MODELS and (Tzschentke, 2001)). These centers are also involved in normal brain functions such as working memory, reinforcement learning, and attention. This article briefly summarizes the main roles of dopamine in particular with respect to recent modeling approaches.