Recreational use of "ecstasy" (MDMA; 3,4-methylenedioxymethamphetamine) is associated with long-lasting effects on metabolism in the human brain. The investigators propose to investigate whether chronic use of "ecstasy" is associated with impairment in motor skills and function of the dopaminergic system in recreational users of "ecstasy" compared with healthy volunteers. This will be done by scanning control subjects and "ecstasy" users at baseline and after performing on a motorbike riding computer game, while imaging dopamine in vivo with I123-IBZM (a D2 receptor radiotracer), using single photon emission computed tomography (SPECT).