Positron Emission Tomography (PET)

Positron Emission Tomography (PET) was developed by Michael Phelps. It depends on the introduction of tracers into the body by either injection or inhalation. PET shows images of the amount and localization of these radioactive molecules. It could be neurotransmitters, drugs, tracers for blood flow or glucose. As a matter of fact, it produces images of normal as well as diseased living biological processes in the body. The major application of PET is in the assessment of metabolic activities and neurotransmitters.

The PET of brain records the metabolism of radioactively labeled glucose (such as fluorodeoxyglucose) in different regions of the brain. As you know, glucose is the only source of energy that the brain uses. Since fluorine 18 has a half-life of about 17 minutes, it is quickly transported to the brain and positrons are emitted. The collision of these positrons with electrons generates gamma rays. A computer maps these rays and produces images of the brain. Given below are the PET images during visual stimulation.

PET of visual stimulation (Source: UCLA School of Medicine )

A large number of published studies have used PET images and reported brain-behaviour association for whole range of activities.

Some examples of use of PET in behavioural studies are elaborated here.