Although meditation practitioners have known the benefits of meditation for thousands of years, it is only now that scientific research is beginning to prove that meditation has a positive effect on us on a physiological level.
It has recently been discovered that the brain has the ability to change its structure and function—strengthening and expanding circuits that are frequently used and weakening and shrinking those that are rarely engaged. This flexibility in the brain is what is called ‘neuroplasticity’.
Previously documented by research on professional musicians that shows changes in the brain related to frequently repeated movements of the fingers, recent tests were conducted on experienced meditation practitioners in universities in the United States.
The tests were carried out on practitioners with up to forty thousand hours of meditation experience, and involved different kinds of meditation practice. They showed a remarkable range of results, such as:
• a high level of activity in the parts of the brain that help to form positive emotions, such as: happiness, enthusiasm, joy, and self-control,
• a decreased level of activity in the parts of the brain related to negative emotions like depression, self-centeredness, and a lack of happiness or satisfaction,
• a calming of the section of the brain that acts as a trigger for fear and anger,
• the ability to reach a state of inner peace even when facing extremely disturbing circumstances, and
• an unusual capacity for empathy and attunement to emotions in other people.
It is interesting that when practitioners meditated on ‘non-referential, all-pervasive’ compassion , the regions of the brain responsible for planned action were activated, as if they were poised and ready to go to the aid of those in distress.
These findings seem to show that training the mind through meditation can have an extremely significant impact on the function of the brain. It appears that emotional tendencies can be altered, and destructive tendencies can be lessened.
 “The state of unconditional loving-kindness and compassion is described as an ‘unrestricted readiness and availability to help living beings.’ This practice does not require concentration on particular objects, memories, or images, although in other meditations that are also part of their long-term training, practitioners focus on particular persons or groups of beings. Because ‘benevolence and compassion pervades the mind as a way of being,’ this state is called ‘pure compassion’ or ‘nonreferential compassion’ (mik mé nying jé in Tibetan).
— Antoine Lutz, Lawrence L. Greischar , Nancy B. Rawlings , Matthieu Ricard and Richard J. Davidson, ‘Long-Term Meditators Self-Induce High-Amplitude Gamma Synchrony During Mental Practice’.
Fig. 1. High-amplitude gamma activity during mental training. (a) Raw electroencephalographic signals. At t = 45 s, practitioner S4 started generating a state of nonreferential compassion, block 1.
Fig. 3. Absolute gamma power and long-distance synchrony during mental training. (a) Scalp distribution of gamma activity during meditation. The color scale indicates the percentage of subjects in each group that had an increase of gamma activity during the mental training. (Left) Controls. (Right) Practitioners.
For more details: http://www.pnas.org/cgi/content/full/101/46/16369