Quoted in a review in The New York Review of Books of her new book, "The Autistic Brain: Thinking Across the Spectrum", Temple Grandin writes:
Researchers...can’t assume that if a patient is exhibiting abnormal behavior and the scientists find a lesion, they’ve found the source of the behavior. I remember sitting in a neurology lecture in graduate school and suspecting that linking a specific behavior with a specific lesion in the brain was wrong. I imagined myself opening the back of an old-fashioned television and starting to cut wires. If the picture went out, could I safely say I had found the “picture center”? No, because there are a lot of wires back there that I could cut that would make the TV screen go blank.
The picture depends not on one specific cause but on a collection of causes, all interdependent. And this is precisely the conclusion that researchers in recent years have begun to reach about the brain—that a lot of functions depend on not just one specific source but large-scale networks."
So, if you ever hear that fMRI can tell us people’s political preferences, or how they respond to advertising, or whether they’re lying, don’t believe it. Science is nowhere near that level of sophistication yet—and may never be.