Friday, June 4, 2010
Brian imaging refers to a number of techniques that result in images that show which areas of the brain are active. Of of these techniques, positron emission tomography (PET) it was introduced in 1976. The PET procedure a person is injected with a low does of radioactive tracer that is not harmful. The tracer enters the bloodstream and indicates the volume of blood flow. With PET scans researchers were enabled to track changes in blood flow to determine which brain areas were being activated. To use this tool, researchers developed the subtraction technique, in whcih brain activity is measured in two conditions: (1) an initial condition, before the stimulus of interest is presented and (2) a test condition in which the stimulus of interest is presented.