In brief, when using magnetic resonance imaging (MRI) to research meditation, the signal of most relevance to meditation research is driven by a difference in the blood oxygenation levels in capillaries and veins compared to the arteries during a particular task (Russell, 2003). Deoxygenated blood is paramagnetic (attracted to a magnetic field) as opposed to when it is oxygenated. On presentation of a specific stimulus, oxygenated blood flow will increase locally within an “active” region of the brain. This will cause deoxygenated blood levels to decrease and subsequently leads to a signal detected by the fMRI apparatus.