For graphs and data, this published paper[1] is referenced by the book mentioned in the article. I quote the book below[2], which has only slightly more detail

For graphs and data, this published paper[1] is referenced by the book mentioned in the article. I quote the book below[2], which has only slightly more detail than the article (I bought the book hoping to see more data, a waste) [1] http://www.pnas.org/content/101/46/16369.full.pdf http://www.pnas.org/content/101/46/16369.full.pdf Long-term meditators self-induce high-amplitude gamma synchrony during mental practice. Antoine Lutz, Lawrence L. Greischar, Nancy B. Rawlings, Matthieu Ricard, and Richard J. Davidson [2] (from the book) "Gamma, the very fastest brain wave, occurs when differing brain regions fire in harmony, like moments of insight when different elements of a mental puzzle “click” together… In the yogis, gamma oscillations are a far more prominent feature of their brain activity than in other people… on average the yogis had twenty-five times greater amplitude gamma oscillations during baseline compared to the control group. "No brain lab had ever before seen gamma oscillations that persist for minutes rather than split seconds, are so strong, and are in synchrony across widespread regions of the brain.