Aftanas et al. (2001) conducted a well designed study of EEG on novice and advanced sahaja yoga meditation practitioners. During meditation substantial changes in midline alpha-theta power, rather than gamma power, distributed more or less symmetrically in the fronto-parietal parts of the brain, occurred in a pattern that was significantly repeatable from subject to subject. Most significantly these changes correlated significantly with the participants’ self-reported experience of mental silence and were more pronounced in the advanced meditators. Thus the mental silence state of sahaja yoga meditation was associated with changes in central nervous system activity that are both reproducible and correlate with subjective experience of meditation. This adds further support to the idea that mental silence may be as much a biological phenomenon as it is a conceptual one. In other words, mental silence may even have a neurophysiology unique to that state of consciousness.