Long-term meditators self-induce high-amplitude gamma synchrony during mental practice PNAS paper of 2004: https://www.pnas.org/doi/full/10.1073/pnas.0407401101 Mingour Rhinpoche who participated had to do 3 meditation techniques: 2. concentration 3. loving kindness and compassion But one practice is enough, as Osho said, and that is for instance widnessing the breath