Tuesday, 18 March 2014

Gamma: unconditional loving-kindness and compassion

Antoine Lutz and others (2004) studied the EEG gamma band activity in long term meditators in contrast to controls new to meditation.  The type of meditation studied was "objectless" loving-kindness and compassion meditation as practiced in the Tibetian Buddhist tradition.  The authors looked at baseline resting state prior to meditation, during meditation, and baseline resting post meditation in the long-term meditators and the controls.  They examined the ratio of fast wave activity (25-42 Hz.) to slow wave activity (4-13 Hz.), absolute gamma, and gamma phase-synchrony measured over long distance electrodes.  They found that for the practitioners compared to the controls the ratio of fast wave to slow wave activity was higher prior to, during, and after meditation in medial frontoparietal electrodes.  Again, for the practitioners compared to the controls, absolute gamma at bilateral parietotemporal and midfrontal electrodes was higher, and the size of phase-synchrony patterns increased for practitioners during meditation.  The authors also found that the extent of training influenced the spatial distribution of gamma phase-synchrony patterns.

The authors conclude that their study provides evidence that meditation practice of the type studied results in increases in the level of gamma activity during meditation and that baseline levels are higher for long-term practitioners before and after meditating.  Their study is consistent with the idea that attention and affective processes, which gamma band activity reflects, can be trained.  Their study demonstrates that this type of objectless meditation has a different profile than concentration meditation characterized by increases in slow alpha or theta during meditation (Shapiro, 1980).

Lutz, A., Greischar, L. L., Rawlings, N. B., Ricard, M., & Davidson, R. J. (2004). Long-term meditators self-induce high-amplitude gamma synchrony during mental practice. Proceedings of the National Academy of Sciences of the United States of America101(46), 16369-16373.

Shapiro Jr, D. H. (1980). Meditation: Self-regulation strategy and altered state of consciousness. Aldine.

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