Using brain imaging techniques, investigators measured brain activity of an advanced Tibetan Buddhist meditator. The results showed an increase of blood flow during the peak of meditation to the left prefrontal area of the brain. Other areas which showed increase in activity were the right and left thalamus, and caudate nucleus. Areas which showed a deficit in activity were the right sensory-motor cortex and the left hippocampus (with the latter showing a marked decrease). The lateral parietal lobe on the right showed an decrease in activity while the left showed an increase. The results were in accord with a theory of brain activation during meditation from earlier studies.

Note that SPECT (Single-Photon Emission Computerized Tomography) is a brain imaging technique that uses radioactive dyes to track metabolic activity in the brain. (Zach Rowinski 2005-03-05)