alan little’s weblog
gamma synchrony
18th November 2004 permanent link
Long-term meditators self-induce high-amplitude gamma synchrony
Experienced Tibetan Buddhist meditators practicing “unconditional loving-kindness meditation” generate the highest levels of gamma synchrony that have ever been measured in trials of normally-functioning brains, and still have significantly higher base levels before and after meditation than a control group of students with rudimentary meditation training. General discussion; pdf of the technical paper.
So what is “gamma band synchrony” anyway? Google tells us that it is strongly present in musicians listening to music (really listening to music … is actually quite an advanced form of meditation)
It “may reflect one way in which the brain ‘integrates’ activity from the plethora of its ongoing parallel processes”. It “has been related both to gestalt perception and to cognitive functions such as attention, learning, and memory”.
Patients with schizophrenia had significantly reduced gamma phase synchrony.
There is one clear problem with the study, that the authors do partly address: the meditators are mostly middle-aged Tibetan monks; the control group are American college students. So, are the differences they are measuring actually brought about by meditation practice and not by age, by cultural differences between America and Tibet, or by people who already have these characteristics pre-selecting themselves for monastic life? The authors do address these questions, and say no: the difference they measured correlates more strongly with length of meditation training than with age. Clearly more research needed in this area though: it would be reassuring to see a study that compared middle-aged Tibetan monks to a control group of middle-aged Tibetan non-monks, and/or one that followed novice monks at various stages in their training.
I find studies like these fascinating. From a yoga student point of view, it’s clear that yogis and buddhist meditators for thousands of years have been on to something real that western science is just beginning to scratch the surface of understanding. And from a software point of view(*), we [“we” = neuroscientists] are trying to reverse engineer a system where the software is rewiring the hardware it runs on at runtime, with only the crudest ways of measuring the outward state of the system. This is something like, I don’t know … trying to understand how Photoshop works by measuring the temperature of the cpu and the amount of hard disk activity, guided by a vague second hand description of the picture on the screen. (Or something. Clearly this analogy needs more work). Only the system you’re trying to study is orders of magnitude more complex than (even) Photoshop. It’s amazing that neuroscientists manage to get anywhere at all.
Is a study of Buddhist meditators necessarily relevant to yoga? I think so. I don’t claim to know much about the similarities and differences between Hindu and Buddhist theology & philosophy, but what I’ve read here and elsewhere about Tibetan meditation seems similar enough to what I read in Patanjali’s Yoga Sutras that I’m fairly confident that the mental states aimed at are similar, even if the techniques used look outwardly very different.
Link from the psychology and neuroscience of religion thread in the ezboard ashtanga yoga discussion group.
(*) My working assumption is that the mind is, at least in principle, explainable in purely material terms as software processes running on hardware – no spirit required. It may be that the complexity of the human mind is beyond the capacity of the human mind to grasp; it may be that quantum uncertainty makes it impossible in principle to fully understand it. But ultimately it’s still all just quanta and the laws of physics.
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