When the Buddhist subjects reached their self-reported meditation peak, a state in which they lose their sense of existence as separate individuals, the researchers injected them with a radioactive isotope that is carried by the blood to active brain areas. The investigators then photographed the isotopes distribution with a special cameraa technique called single-photon-emission computed tomography (SPECT).
The height of this meditative trance, as they described in a 2001 paper, was associated with both a large drop in activity in a portion of the parietal lobe, which encompasses the upper back of the brain, and an increase in activity in the right prefrontal cortex, which resides behind the forehead. Because the affected part of the parietal lobe normally aids with navigation and spatial orientation, the neuroscientists surmise that its abnormal silence during meditation underlies the perceived dissolution of physical boundaries and the feeling of being at one with the universe. The prefrontal cortex, on the other hand, is charged with attention and planning, among other cognitive duties, and its recruitment at the meditation peak may reflect the fact that such contemplation often requires that a person focus intensely on a thought or object.