The type and extent of structural damage to brain tissue can be determined by autopsy (i.e., post mortem) examination of the brain’s components and individual nerve cells (i.e., neuropathological evidence). In addition, neuroradiological techniques, such as MRI and CT scans, allow the brain to be viewed inside the skull of a living person. Other neuroimaging techniques (i.e., functional neuroimaging) measure active brain functioning. Functional neuroimaging can reveal changes in the blood flow in and around the brain, brain metabolism, and brain electrical activity generated by nerve impulses (i.e., neurophysiological measures).5 One type of neurophysiological measure, event-related potentials (ERP’s), consists of brain waves recorded from scalp electrodes while a person is presented with specific pieces of information or stimuli. Scientists use computers to translate the information obtained from ERP’s and other functional neuroimaging measures into meaningful pictures that, in turn, make it possible to view brain functioning while a person is thinking or performing a task.
