http://www.nejm.org/doi/pdf/10.1056/NEJMoa1204471
fMRI is a technique that allow us to see inside your mind. Other studies such as CT and MRI let us visualize anatomy. They take a snapshot of what the brain looks like. fMRI, on the other hand, superimposes an image of which parts of the brain are metabolically active on the anatomy of the brain. This technique allows us to see which parts of the brain are thinking. Keep in mind that the brain is active in a lot of ways that we don’t realize. When you feel the joy of victory or the agony of defeat, many parts of the brain are active to create those feelings.
With fMRI, we are able to see the brain in action. We can see what parts of the brain are active and by controlling what the subject experiences, we are able to see what parts of the brain are responsible for what experience.
Up until very recently, when someone told me they were experiencing pain, I had no way to confirm or disprove it. I had to take someone at their word. Unlike a symptom with a sign I can see-like a rash, there is nothing to look at when someone is having pain. Sometimes there is a broken bone that accompanies the pain that I can point to as the cause, but very often, figuring out what is causing the pain is not so clear cut and often I am unable to find anything at all to explain the symptom. Things are becoming much clearer now. In the case of pain, I can pinch you to induce it, or shock you to cause pain and then look and see which parts of your brain are involved in the experience of pain you feel from my pinch, or electric shock. This study demonstrates that it is becoming very possible to see experimental pain as it is being experienced. Soon we will be able to see any pain, not just experimental pain. Finally we will have a test to determine not just where the pain is coming from, but how much pain you are actually experiencing.