ventral tegmentum

ventral tegmentum or ventral tegmental area (VTA)

1. A part of the midbrain, close to the substantia nigra and the red nucleus, that contains dopamine and serotonin.
2. The part of the mesencephalon that projects to the nucleus accumbens via the mesolimbic pathway and to the cortex via the mesocortical pathway

It should be noted that ventral tegmental area has near 4,000 hits on pubmed.com, while ventral tegmentum has less than 300. This is because ventral tegmentum is somewhat ambiguous and only colloquially refers to the VTA or ventral tegmental area.