Techniques to Learn About Structure and Function for AP Psychology (page 2)

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By — McGraw-Hill Professional
Updated on Mar 4, 2011

Measuring Brain Function

Scientists have developed a number of tools to measure the brain functions of people. An EEG (electroencephalogram) is an amplified tracing of brain activity produced when electrodes positioned over the scalp transmit signals about the brain's electrical activity ("brain waves") to an electroencephalograph machine. The amplified tracings are called evoked potentials when the recorded change in voltage results from a response to a specific stimulus presented to the subject. EEGs have been used to study the brain during states of arousal such as sleeping and dreaming, to detect abnormalities (such as deafness and visual disorders in infants), and to study cognition. Another technology, positron emission tomography (PET) produces color computer graphics that depend on the amount of metabolic activity in the imaged brain region. When neurons are active, an automatic increase in blood flow to the active region of the brain brings more oxygen and glucose necessary for respiration. Blood flow changes are used to create brain images when tracers (such as radioactively tagged glucose) injected into the blood of the subject emit particles called positrons, which are converted into signals detected by the PET scanner. Functional MRI (fMRI) shows the brain at work at higher resolution than the PET scanner. Changes in oxygen in the blood of an active brain area alters its magnetic qualities, which is recorded by the fMRI scanner. After further computer processing, a detailed picture of that local brain activity emerges. With new brain imaging technology, psychologists can explore far more about our abilities than ever before, from well-known systems like perception to less understood systems like motivation and emotion.


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