Do humans have a "dominant" neurotransmitter system/sensitivity within their brain?
Dr. Helen Fisher's conclusions are plain bunkum. What does it even mean when she says associated with a particular neurotransmitter? The sheer work required to even get at this question is vast and difficult so it is unsurprising that she is venturing as much as a guess.There is scientific evidence to support different neurotransmitters systems can go awry in diseases but Fisher is overinterpreting the literature. Take a look at the neurotrasmiter table and you can see what each does and how malfunctions can result in certain diseases.
http://en.wikipedia.org/wiki/Neurotransmitter

Also testosterone and estrogen are thought of primarily as hormones not neurotrasmiters.So Fisher is saying women(who have more estrogen) are better negotiatiors whereas men(more testosterone) are directors. Even these banal conclusions are contentious and debatable.