PNAS paper from 2004:
Long-term meditators self-induce high-amplitude gamma synchrony during mental practice:
https://www.pnas.org/doi/10.1073/pnas.0407401101
We don t need brain scanners & Lhagsam Tibetan Meditation in Zurich, Richard R. Davidson, Psilocybin, Rob ter Horst and the other devices and methods presented on the 3263 pages under www.petergamma.org. But we need the books recommended under www.petergamma.org, and a full-time training of around 13 years in solitary retreat, as Dilgo Khyentse Rinpoche did it:
And then we become enlightened, which is according to the Buddhist teachings equivalent to be completely mentally healthy. And if your budget does not allow this, who does not help people who suffer from being not completely mentally healthy?