Friday, May 14, 2010

EEG of Jhanas

EEG Power and Coherence Analysis of an Expert Meditator in the Eight Jhanas is a working paper that describes the EEG differences between resting state and Jhana for a single subject, Leigh Brasington (Leigh discusses the study on Youtube). Jhanas are altered states of consciousness that meditators go into typically as a result of a concentration style practice. The Jhanas are described as some of the most pleasurable experiences that a human can have, and Leigh has the envious ability to reliably go in and out of these states.

I was mainly interested in the maps of various power bands while in Jhana compared to the resting state. These provide some information on the EEG changes, but of course these are relative to Leigh's resting state, not a normative sample. Which may be a good thing, in terms of what we're looking for, but one thing I'd also like to see is how Leigh's resting state compares to a normative database.

The maps are based on a 256-channel Geodesic Sensor Net and I had to dig up some information to get an idea of how to think of the sites in a 10-20 or 10-10 kind of way. Black boxes represent higher amplitudes, white boxes represent lower amplitudes.  I found myself struck by the beauty and symmetry of the patterns.

A lot of the effects are concentrated in the prefrontal area, roughly in triangles formed by Fp1-F3-F7 and Fp2-F4-F8, or to put it more simply, the median of these areas might fall a bit below F3 & F4.   There were a couple of areas around FC3 & FC4 where gamma was decreased, this would be in contrast to Davidson's research that found gamma increases in those areas in his study of Tibetan monks practicing loving kindness meditation. In the aforementioned areas during Jhana,

  • Theta 4-6Hz was lower
  • Alpha 8-10Hz was higher
  • Alpha 10-12Hz was much higher
  • Beta 12.5-25Hz was much higher
  • Gamma 25-42Hz was much higher, probably overall the biggest effects

Theta 4-6Hz and Alpha 6-8Hz were higher in the Cz-Pz area, radiating out towards F3 and F4. Alpha 10-12Hz was slightly lower around Pz, which is somewhat at odds with Newberg's research showing less activation (i.e. presumably more alpha) in that area for contemplatives experiencing oneness.

All in all, very interesting stuff, this is the exact kind of thing I've been searching for, and I look forward to seeing the final paper, which looks like it will have a section on coherence, as well as more research along these lines.

No comments:

Post a Comment