meditation and the EEG

Buddhist monk Matthieu Ricard in preparation for conducting an electroencephalography (EEG) test at the EEG facility in the Waisman Center at the University of Wisconsin-Madison. In his meditation Matthieu produced the highest amount of Gamma waves ever recorded.

The more I read about the effect of meditation the more amazed I got. Meditation influences several chemical equilibriums to go back to normal, releases anti-stress hormones, has effect on the thickness of the cortex and even may stop the aging of our DNA.

Different meditations

There are different kinds of meditation which can be devided by the focus they use.

* Concentration on breath, sound, or repeating a mantra narrows the focus.
* Mindfullness is “perception without excluding anything” and gives a wide angle focus.
* Samatha (peace, silence, no performance, mindlessness) is a traing in no focus.

These different practices will have another effect on the mind and the EEG.
In some studys (like transcentental meditation) researchers found that the amount of alpha in the EEG was raised but other studys did not confirm this. Some meditation techniques use visualization and others do not. Some techniques are a bit like selfhypnosis, which has no effect on the alpha waves but theta waves may increase substantially.

Meditation and Gamma waves
As investigators agree, temporal synchrony is needed for conscious awareness.
Experiments on Tibetan Buddhist monks have shown a correlation between transcendental mental states and gamma waves. When the monks were told to generate an objective feeling of compassion during meditation, their brain activity began to fire in a rhythmic, coherent manner, suggesting neuronal structures were firing in harmony. This was observed at a frequency of 25 to 40 Hz, the rhythm of gamma waves. These gamma-band oscillations in monks were the largest seen in humans. Gamma waves may relate to peak performances, and expanded (non dual) consciousness.

Meditation and the DMN
As the aim of meditation is to deminish mind-wandering (mental travel) and self referential thoughts, it might calm down (de-activate) a brain structure called DMN (default mode network). Read more

Meditation and neurofeedback
A great article about meditation and EEG is by Tracy Brandmeyer and Arnoud Delorme and was published in " frontiers in psychology" . Distributed under the terms of the Creative Commons Attribution License (CCBY). Read the article

Some more links
Youtube video: Biofeedback Meditation: A New Gateway to an Ancient Path
Meditators and gamma synchrony Read more
Frontiers in neuroscience : Neurophysiological correlates of various mental perspectives
Frontiers in neuroscience : Neural networks enhanced by satyananda yoga.