Both norepinephrine and dopamine (sometimes called the "feelgood" chemical, because it's associated with motivation and pleasure) are the triggers for communication along the pathways between the basal ganglia, deep in the brain, and the prefrontal cortex, sometimes referred to as the brain's command centre because it controls executive functions such as problem-solving, attention and reasoning. It's believed (though it's hard to find strong evidence) that ADHD results from function reduction in dopamine and/or norepinephrine levels in the brain.
Nikki Barrowclough
31 March 2007
The Age