Well, I've been looking, and mostly what I've been able to find is references to papers that show strong correlation with Buddhist monks and exceptional gamma waves. The paper I'm thinking of may have not been reproducible, and fallen off the radar. I would have seen it no later than 2011. I might be quoting a book on neuroscience as well (I went through a phase where I was looking at neuroscience for inspiration for AI research). I think the idea was that people who meditate while doing certain types of "mindless" tasks seem to be able to hold 1 wave around that task, while holding another wave around other thoughts. What I can't remember is if this was a one gamma wave per hemisphere scenario, or 2 for the whole brain.

If you're interested at least in consciousness and brain waves, you could do worse than to look into reading some of the references in "States of Consciousness: Experimental Insights into Meditation, Waking, Sleep and Dreams" Dean Cvetkovic & Irena Cosic Editors