Basically, imaging techniques are either structural or functional. A CAT scan or MRI captures an image of your brain's structure. MRI, fMRI, PET, or SPECT scan depicts what your brain is doing over a specific period of time ranging from seconds to minutes. Brain actifity leads to changes on blood flow, elecgrical discharges, and magnetic fields. (Restak, Richard, MD. The Naked Brain. p 10-13. NY:Three Rivers Press, 2006.)

Brain imaging technologies (PET, fMRI) are modalities that show the brain neighborhoods that are active during a specific mental activity. (Schwartz, Jeffrey M., MD, and Sharon Begley. The Mind & the Brain. p 23-24. NY:Regan Books, 2002.)

Three principal types of brain scans include: CAT or CT, MRI, and PET (160, Greenfield, Susan, Con. Ed. Brain Power, Working out the Human Mind. The Ivy Press Limited, 1999.

Brain scanning techniques are showing just how precisely it is possible to pin down even the most sophisticated and complex machinations of the human brain. MRI, PET, fMRI, NIRS, EEG, MEG, etc. (Carter, Rita, Ed. Mapping the Mind. p 25-27. CA:University of California Press, 1998.)

Transcranial Magnetic stimulation (TMS) involves plastic-enclosed coils of wire placed on the outside of the skull. When activated, a magnetic field is produced that passes through the skull and induces a current in the brain that locally activates the nerve cells. Acitivy of parts of the brain can also be inhibited to allow study of what a specific area does when it is disconnected from the processes of other areas. (Gazzaniga, Michael S. Who's In Charge? p 113. NY: HarperCollins Publishers, 2011)