The result was the scans that Prof. Davidson projected in Dharamsala. They compared brain activity in volunteers who were novice meditators to that of Buddhist monks who had spent more than 10,000 hours in meditation. The task was to practice "compassion" meditation, generating a feeling of loving kindness toward all beings.via WSJ.com - Science Journal (Journal Article (pdf))
In a striking difference between novices and monks, the latter showed a dramatic increase in high-frequency brain activity called gamma waves during compassion meditation. Thought to be the signature of neuronal activity that knits together far-flung brain circuits, gamma waves underlie higher mental activity such as consciousness. The novice meditators "showed a slight increase in gamma activity, but most monks showed extremely large increases of a sort that has never been reported before in the neuroscience literature," says Prof. Davidson, suggesting that mental training can bring the brain to a greater level of consciousness.
Using the brain scan called functional magnetic resonance imaging, the scientists pinpointed regions that were active during compassion meditation. In almost every case, the enhanced activity was greater in the monks' brains than the novices'. Activity in the left prefrontal cortex (the seat of positive emotions such as happiness) swamped activity in the right prefrontal (site of negative emotions and anxiety), something never before seen from purely mental activity. A sprawling circuit that switches on at the sight of suffering also showed greater activity in the monks. So did regions responsible for planned movement, as if the monks' brains were itching to go to the aid of those in distress.