Brain Scanning Techniques

Brain Scanning Techniques

1. Computerized Axial Tomography (CAT)

   • When an X-ray passes through the head, it is picked up by a detector on the opposite side and is analyzed. The subject lies on a table that slides into a large cylindrical apparatus.

2. Magnetic Resonance Imaging (MRI)

   • Since we know that the concentration of hydrogen differs in different types of tissue, we can use this information to produce a 3D picture of the brain structure.

3. Functional Magnetic Resonance Imaging (FMRI)

   • This method uses the BOLD (brain-oxygen-level-dependent). Similar to MRI, the subjects are also required to carry out a task while their brain is being scanned.

4. Positron Emission Tomography (PET)

   • A radioactive tracer is injected in the subject's bloodstream. This tracer binds to molecules such as glucose.
     • It decays quickly and emits energy. The more active a brain area, the more blood supply it needs, hence the higher the energy level emitted by the tracer.
       • After the injection the subject is placed in a scanner that picks up the energy emissions.

5. Electroencephalography (EEG)

   • When large groups of neurons are activated simultaneously, electric potentials generated by these impulses become detectable on the skull surface.
     • Electrodes can be attached to the scalp to detect this electrical activity.
       • Electrodes are attached to the scalp at predetermined points. The subject is required to lie still for several minutes while the electroencephalogram is generated.