What is it? Functional Magnetic Resonance Imaging (fMRI) is a dynamic new way to locate brain functions. Specifically, it shows which areas of the brain are active when a person thinks, speaks, moves, feels, or remembers. It allows us to see the brain in action. When we speak to each other or listen to someone speak to us, certain areas of our brains become more active. These areas are critical to us because they control our speech, our language and our memory, as well as our sensations and movements. Brain areas are not always active, but as the level of activity changes, the focus of its location changes with each differing cognitive activity.

It is important to be able to locate precisely various areas for each patient, because everyone's functional distribution within eloquent cortex is quite different. Brain organization is like a person's fingerprints: similiar in organization, but very different in the details. These individual differences are important, and fMRI allows us to identify, locate, respect and preserve these vital functions. fMRI produces functional maps which augment anatomical maps.

How is it done? To determine the exact location of speech or memory or motor functions, a patient has a normal MRI scan of his or her brain, but at the end of these scans, specialized fMRI protocols are added. These special protocols make apparent differences in tiny amounts of increased blood flow in the venioles and capillary beds, and they record its location. Each scan takes about 3 minutes, and it is usually necessary to scan differing brain areas, so functional scans normally take about a half to three-quarters of an hour. No contrast agent is injected into the patient, so these scans are completely non-invasive and are safe. Each fMRI patient has to be able to follow very simple instructions while he or she is being scanned, such as listen to a sentence and squeeze a rubber bulb, or follow motor commands, such as wiggle your fingers. Each has to lie very still. Children younger than 13 years old present more challenge as they usually have much greater difficulty lying still for the fMRI sequences. These tiny differences require that the patient lie virtually still during the scan.

What does it tell us? Since functional MRI scans identify clearly and specifically which areas of the brain are involved in movements, such as moving a hand, a wrist, leg, or tongue and lips, fMRI is important for patients who are about to have brain surgery. fMRI scans help to determine in advance each critical brain area for neurosurgical planning. The neurosurgeon might use these results to help guide planning the surgery. fMRI scans tell us which areas of the brain are functional: that is, which areas are controlling some important brain act, such as remembering, listening, talking, or moving, and preserving these functions increases the patient's chances for a normal life.

However, observing these functions requires great precision. Observing differences in blood flow between active areas and less active areas requires "seeing" very small changes (1- 4%). These small differences require that we use statistical analyses of these images to produce reliable results. The large number of images acquired during each session (500-1200 images) necessitates significant effort, manpower, hardware, software, as well as digital storage, to process and analyze these results. These tasks demand image co-registration, mathematical correction for motion and other potential artifactual errors, and require state-of-the-art knowledge to produce reliable and valid results.