All gamblers qualified as PGs because they met five or more DSM-IV-TR criteria for pathological gambling and were otherwise healthy. Of these subjects, 4 PGs had been in cognitive behavioral treatment for their gambling problems 2 to 6 years before the PET study. The severity of gambling symptoms was assessed using the South Oaks Gambling Screen [SOGS ]. All PGs had a minimum lifetime SOGS score of 5 when initially included in the pharmaco-fMRI study , whereas HCs, with the exception of 2 subjects , had a SOGS score of 0. The severity of gambling symptoms was measured again at the time of the PET study using past-year and past-3-month versions of the SOGS . Frequent forms of gambling were assessed using item 1 of the SOGS and are expressed in terms of the percentage of gamblers playing the following games at least once a week for money: slot machines , card games , casino games , sports betting , lotteries , stock market , and bowling, pool, golf, darts, or the like .