A Primer on Imaging

During the past 30 years, increasingly sophisticated imaging techniques have been developed for examining the structure and function of the living brain. Computed tomography and magnetic resonance imaging can each represent a three-dimensional “slice” of brain, showing more detail than a conventional X ray. Functional imaging techniques permit scientists to detect changes in blood flow and energy metabolism. Such techniques include magnetic resonance spectroscopy, magnetic resonance imaging, single-photon emission computed tomography, and positron emission tomography. In addition, electroencephalography records the spontaneous electrical activity of the brain, and magnetoencephalography measures and displays the magnetic field that surrounds the head in association with the electrical activity.