Riemann Zeta
Bluelighter
I wouldn't count noradrenaline out of the equation to produce a good stimulant compound. As long as the compound is lipophilic enough to primarily accumulate in the brain, NET substrates can release central noradrenaline, as well as dopamine in the frontal cortex via the NET (there are more NETs than DATs presynaptically in the prefrontral cortex, so some dopamine gets sucked up by adrenergic neurons). Since amphetamine (both d-amph and dl-amph) has equivalent affinity/efficacy at both the DAT and the NET, it has some decent cognition enhancing effects. d-Methamphetamine does have a greater affinity for dopamine transporters and while it is a more potent stimulant, it is also more hedonic (hence, addictive) with a weaker pro-cognitive effect and is significantly more toxic than amphetamine itself. Noradrenaline can be a good thing, as long as it's not peripherally creepy-crawly and all annoyingly hot and bothered--of course, some dopaminergic activity is essential, otherwise the whole thing just gets disgusting, like (-)-ephedrine, phentermine or atomoxetine.