THE PRIMATE SUBSTANTIA-NIGRA AND VTA - INTEGRATIVE CIRCUITRY AND FUNCTION

A substantial amount of research has focused on the midbrain dopamine system and its role in mediating a wide range of behaviors. In disease s in which dopamine function is compromised, patients exhibit a conste llation of symptoms suggesting that the dopamine system plays an impor tant role in the integration of several functions. We have shown that there are subgroups of dopamine neurons that receive information from limbic and association areas and project widely throughout cortex and striatum, including motor areas. A dorsal tier of dopamine neurons rec eive input from the ventral (limbic) striatum and the amygdala and pro ject widely throughout cortex. A more ventrally located group of dopam ine cells receives input from both the limbic and association areas of striatum and project widely throughout the striatum including the sen sorimotor regions. Through these projections the dopamine system can e ffect a wide range of behaviors. For the most part, structures of the basal ganglia are thought to be organized in parallel pathways. Howeve r, the behaviors affected by basal ganglia disorders can be in part ex plained by the integrative nature of the dopamine system and its Links to motor, limbic, and association areas of the striatum and cortex.