Localization of brain function using magnetic resonance imaging.

When nuclear magnetic resonance images (MRIs) of the brain are acquired in rapid succession they exhibit small differences in signal intensity in positions corresponding to focal areas of activation. These signal changes result from small differences in the magnetic resonance signal caused by variations in the oxygenation state of the venous vasculature. Using this non-invasive functional MRI (fMRI) method, it is possible to localize functional brain activation, in normal individuals, with an accuracy of millimeters and a temporal resolution of seconds. Though numerous technical challenges remain, fMRI is increasingly becoming a key method for understanding the topographical organization of the human brain.