That's really interesting, Bruce. Usually I can't help but roll my eyes at high level interpretations of neurotransmitters like this, but I think you may actually have a plausible point. For what it's worth, I'm not a neuroscientist, but I fully believe that the popular interpretation of dopamine being the "key to addiction and pleasure," is completely misguided.I've seen studies of rats that were drowned with surgically implanted probes monitoring their neurotransmitter levels, and as they drowned to death their brains were flooded with dopamine (very sad, I agree -- I hate this stuff, but it's there, may as well learn from it). That makes no sense. They got pleasure from drowning? Yeah, I don't think so... the problem is that there are dozens of different kinds of dopamine, dozens of different locations for each kind to bind to, etc., etc., etc.. The human brain is so spectacularly complicated that the conclusions most people draw are more like phrenology than science (phrenology being that weird thing that thinks it can deduce your personality and traits by the bumps on your skull).Personally I think that primarily, dopamine is used to direct and influence concentration and attention. That would explain stimulants aiding ADHD sufferers, the poor little mousey (RIP, little guy), gambling, drugs, all of the evidence I've seen -- the pleasure/reward interpretation just doesn't match all of it. Easily mistaken for a "reward cascade," since to enjoy something or find it pleasurable you tend to be focusing on it, so they overlap.A drowning mouse wouldn't feel pleasure or be rewarded by the experience. He would have his entire brain catastrophically focusing on what was happening to try and save himself though.... no, this really doesn't have anything to do with anything. Just me rambling. Anyway, Bruce has a point. You may be susceptible to this to an unusual degree because of an undiagnosed, underlying condition. It may even be so subtle that it doesn't do anything except when you take drugs to intensify the problem. Personally I virtually never get circular thinking no matter how many stimulants I take... overpoweringly compulsive behavior, yes, but not circular thoughts.