The ventral tegmental area is a heterogeneous brain structure that plays a central role in rewarding and aversive experience processing. Studies suggest that several subpopulations within the ventral tegmental area form subcircuits that are differentially involved in rewarding and aversive experiences and that could be individually affected in several neuropsychiatric disorders. Here, we focus on the recent advances concerning the functional description of the three major neuronal subpopulations, in terms of neurotransmitter release, their input and output structures, and their role in controlling specific behavioral outcomes. Several subpopulations within the Ventral Tegmental Area form subcircuits that are differentially involved in rewarding and aversive experiences and that could be individually affected in several neuropsychiatric disorders. We focus on the recent advances concerning the functional description of the three major neuronal subpopulations, their input and output structures, and their role in controlling specific behavioral outcomes. This article is part of a mini review series: "Synaptic Function and Dysfunction in Brain Diseases".