As previously described, there are pathways through the forebrain that are involved in reinforcement of behaviors and in "reward". Electrical stimulation of these sites is highly reinforcing for behavior. Many of these pathways involve dopamine and are commonly affected by drugs of addiction. Habituation in these pathways with chronic administration of addicting drugs is one of the most important targets of addiction research. figure 26 shows the ventral striatal projections to the ventral pallidum which, in turn, projects through the dorsomedial nucleus of the thalamus to limbic areas of cortex. The ventral striatum mostly consists of the nucleus accumbens, which is an important target of dopaminergic projections from the ventral tegmental area.