Heroin Addiction: Anticipating the Reward of Heroin or the Agony of Withdrawal?

Conditioned withdrawal drives heroin intake by decreasing brain reward activity in dependent animals only. Conditioned withdrawal was induced by the presentation of stimuli (tone plus light) previously paired with naloxone. In nondependent rats, naloxone-paired stimuli had no effect on brain reward thresholds or on heroin self-administration. In heroin-dependent rats, naloxone-paired stimuli produced an acute reward deficit that was associated with an increase in heroin consumption.