Читать книгу The Handy Psychology Answer Book - Lisa J. Cohen - Страница 211

PET scan was one of the earlier brain scanning technologies and now has largely been eclipsed by fMRI technology. PET scans work by measuring the decay of a radioactive tracer that has been injected into the blood stream prior to the scan. This allows scientists to map the brain areas with the greatest amount of blood flow. It is assumed that high rates of blood flow in a particular area indicate increased brain activity at that location. PET scans are used to compare blood flow patterns across groups (e.g., in patients with schizophrenia vs. healthy controls) or across activities (e.g., viewing images of drug paraphernalia vs. a nature scene). These days fMRI methodology is used far more frequently than PET because it is less expensive, does not involve radioactive tracers, and has better resolution both across time and across space. In other words, fMRI provides more precise visual information and can take more scans in the same amount of time. But PET still has some important advantages over fMRI. This is because PET’s radioactive tracers can measure substances other than blood flow. Specifically, they can be used to measure the activity of different neurotransmitters, brain chemicals that are centrally involved with psychological processes.

Brain imaging technology allows us to view the workings of a living brain, an extraordinary accomplishment possible only in the last few decades.