LOCALIZATION OF BRAIN-FUNCTION USING MAGNETIC-RESONANCE-IMAGING

When nuclear magnetic resonance images (MRIs) of the brain are acquire d in rapid succession they exhibit small differences in signal intensi ty in positions corresponding to focal areas of activation. These sign al changes result from small differences in the magnetic resonance sig nal caused by variations in the oxygenation state of the venous vascul ature. Using this non-invasive functional MRI (fMRI) method, it is pos sible 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 beco ming a key method for understanding the topographical organization of the human brain.