Electroencephalogram (EEG): measures the electricity of the brain
STATIC PICTURES
Magnetic Resonance Imaging (MRI): person gets into the scan, hydrogen atoms within the body are aligned by a huge magnet beneath the person from within the machine, a brief radio wave disrupts the hydrogen atoms, the electromagnetic energy is released and the change is recorded, giving an image of the brain.
Computerized Axial Tomography (CAT): utilizing x-rays, multiple pictures are taken of the brain from within the machine at different angles.
FUNCTIONAL PICTURES (the brain in action)
Positron Emission Tomography (PET): the subject is injected with a radioactive isotope-- 2-deoxyglucose-- then two radioactive rays are shot through the body (while the person in inside the PET). From these gamma rays, glucose can be highlighted on the scan and show the areas where more sugar is used in the brain. The more active areas, as theory goes, will have higher levels of glucose, thus creating a picture of the brain.
Functional Magnetic Resonance Imaging (fMRI): measures the magnetic change in the brain when oxygen is released by the hemoglobin in the blood. More oxygen is supposedly used in the more active areas.