Functional magnetic resonance imaging
What is it and what can it tell us about the brain?
If you’ve watched a medical documentary during the past few years, the chances are you will have seen a volunteer fed into a functional magnetic resonance imaging (fMRI) scanner to examine the brain’s role in the issue under investigation. The scanner produces coloured images of the volunteer’s brain, showing areas of high activity. These techniques have been used to investigate a wide range of phenomena, including sleep, dementia, obesity, memory formation, stress, and even lie detection.
In contrast to conventional magnetic resonance imaging techniques, in which images focus on brain anatomy, fMRI probes the dynamic organisation of the brain. Images are acquired while the subject performs a task in the scanner, and these images are then analysed to determine the brain regions involved in the execution of the task. Thus the structure of the brain is mapped to its function.
A task might entail listening to an auditory stimulus (for