Ventral Tegmental Area (VTA) is the area that synthesizes dopamine, which then sends to nucleus accumbens. Nucelus accumbens is the pleasure center, and it is stimulated by the neurotransmitter dopamine from VTA. VTA also sends dopamine to prefrontal cortex which regulates and controls these impulses. The locus coeruleus is the area packed with norepinephrine; and when stimulated by a lack of the addictive substance, will drives the person to do anything necessary to obtain a fix.
See figure: 'Neurochemical targets of methamphetamine. The picture shows the...' from publication 'The Effects of Locus Coeruleus and Norepinephrine in Methamphetamine Toxicity' on ResearchGate, the professional network for scientists.