fMRI stands for functional Magnetic Resonance Imaging. An fMRI scanner is a very large magnet that uses a safe, non-invasive magnetic field to take a picture of the brain while it is working.

The brain is made up of about 1 trillion tiny nerve cells called neurons. When the brain is working, these neurons send and receive signals to each other. The more they send and receive signals, the more oxygen they need from the blood flowing around in the brain. This means that areas of the brain with heavily signaling neurons get more blood flow. fMRI uses a magnetic field to measure increases in blood flow all over the brain. This way, the fMRI scan allows us to see what areas of the brain are working harder than others.

fMRI is a great technique for understanding how the brain works. By having people perform simple tasks during the scan (such as listening to sounds or looking at pictures) we can see how the brain responds. So far, fMRI has enriched our understanding of various brain diseases and disorders as well as how the normal brain works and develops. Eventually, these discoveries will deepen our understanding of the healthy brain and help us diagnose and treat persons with brain disorders.