It has been noted that “virtually any manipulation that produces an enduring change in behavior leaves an anatomical footprint in the brain” (Kolb et al., 2003, pp. 3–4). In the case of drug use, this manipulation involves the systems and neural networks that may developmentally be already suboptimally prepared for effective psychological regulation. It is well known that intake of virtually all drugs activates the dopaminergic system (DS), which supports its role in the origins of common addiction liability and its variation (Vanyukov et al., 2003b). Whereas specific drugs enter the common circuit at different points, the shared structures include neurons of the ventral tegmental area (VTA), which are connected to the basal forebrain (the nucleus accumbens, olfactory tubercle, amygdala, and frontal and limbic cortices), and opioid peptide neurons within these connections (Koob and Le Moal, 2001). The DS therefore is involved with mechanisms acting both pre- and post-onset of drug use.
