Dopamine is our arousal and stimulation neurotransmitter. We associate dopamine with rewards as it controls our appetite for sex, eating, pleasure and even creative thinking. Too little dopamine can lead to depression, but too much can lead to dependence on the agent doing the stimulating.
http://www.healthcentral.com/slideshow/getting-to-know-your-5-essential-brain-chemicals#slide=4
Wikitruth
Fix The Philippines