BSR and drugs of addiction produce their rewarding effects through shared neuroanatomical and neurochemical mechanisms. Studies using lesion, pharmacological, and anatomical mapping of the brain have revealed that many drugs of abuse (e.g. amphetamine, cocaine, opioids, nicotine, etc.) activate the reward circuitry of the MFB, which is similarly activated by stimulation to achieve BSR. The neuronal axons of the mesolimbic dopamine system, a key component of the reward circuitry, generally have high thresholds for stimulation. However, these thresholds can be increased or decreased by drug administration, influencing sensitivity to intracranial stimulation and ICSS behavior.