Our Bloggers

Marieke van Vugt

New evidence for changes in brain waves associated with meditation

One of the first findings on the effects of meditation on the brain were very large amounts of gamma brain waves reported in long-term practitioners (Lutz et al (2004)). An important problem with that study was the fact that we had no idea how these gamma waves came about. Were they caused by the meditation or were the people that took part in this study simply weird people? Recently, a new study was published that shed light on this issue.

This study was done on the participants of the Shamatha Project. In this ambitious project, a group of 60 people was randomly assigned to a three-month retreat or to a wait-list control condition. They were all tested before, half-way, and at the end of the retreat. This study focuses on a test where they meditated for 12 minutes while their EEG is being recorded. The researchers hypothesized that meditation would be associated with changes in alpha and beta oscillations (those are slower waves than the gamma waves).

They found that beta oscillations over a group of central electrodes (see image) recorded during the shamatha meditation practice in which participants focused on their breath decreased in amplitude over the course of the retreat. The authors speculate that this reduction in beta oscillations reflects an increased readiness for perception, and decrease of mental noise. Indeed, previous studies on this subject pool have shown that these people improved in perceptual clarity over the course of the retreat (MacLean et al, 2010). It is a pity that the authors did not directly correlate performance on a perceptual task to this decrease in beta oscillations.

They also showed that the peak frequency of slightly slower brain waves, the alpha waves, decreased for the meditators more than for the wait-list control. This "individual alpha frequency", as it's called, has been associated with cognitive capacity. The authors suggest that "After intensive training, increased attentional stability may reduce the attentional resources required to sustain attention on the sensations of the breath." In short, intensive practice of meditation seems to increase cognitive capacity and increase perceptual clarity. The authors did not find this increase in more high frequency (gamma oscillations) that was previously reported in very long-term meditators. It could be the case that people need to meditate much longer before that can be observed. It could be also the case that that previous finding was related to muscle artifacts, or that that gamma increase can only be observed with the type of meditation ("open monitoring") that those practitioners were doing, which is very different from the focused attention meditation in the current study.

In short, I think it's very exciting that some more studies are starting to show how meditation changes your brain waves.