Read Montague is interested in the human dopamine system -- or, as he puts it in this illuminating talk from TEDGlobal 2012, that which makes us "chase sex, food and salt" and therefore survive.
Specifically, Montague and his team at the Roanoke Brain Study are interested in how dopamine and valuation systems work when two human beings interact with each other.
Here are some great Ted Talks about the brain...
However, it is missing my favourite, which I watch with grade 12's...
Sebastian Seung: I am my connectome