They developed a Pavlovian-type association by flashing a geometric shape on a computer screen and giving a squirt of juice into the volunteers' mouths. However, the volunteers did not realise that they were being conditioned in this way - they were simply told to press a button to indicate on which side of the screen the shape had appeared.Link
The team measured how the volunteers had become conditioned by measuring their anticipation of the juice squirts following an image by measuring the dilation of their pupils...
The fMRI scans revealed significant responses reflecting learning in the ventral midbrain and the ventral striatum. Crucially, they found that the strength of the response correlated with the volunteer's like or dislike of the juice.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.