ABSTRACT
In the past researchers could only study the living brain indirectly, often by observing malfunctions caused by disease or accident. The workings of the normal brain were next to impossible to see in detail because the brain is protected by the skull, enveloped in a tough membrane and cushioned in fluid, making it difficult to access for measurements or observation. Now, nuclear medicine techniques such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging are making dramatically visible the actual biochemical and metabolic activity of the brain. (Another important technique, functional magnetic resonance imaging (fMRI), will be covered in Chapter 8.) These techniques have been used to study clinical depression, Alzheimer's disease, schizophrenia, and numerous other mental illnesses. Even more striking, these imaging methods have made it possible to study brain function in healthy persons to determine, for example, which parts of the brain are involved in processing vision or understanding speech. Information from such imaging techniques can also be used to map out the brain's functioning prior to surgery, resulting in operations with a reduced likelihood of causing serious damage.
