The mental processing behind meditation

Here’s a summary of an interesting article written by researchers based in Wisconsin that has classified meditation types into three broad categories based on their underlying brain processes.

1. Attentional
2. Constructive
3. Deconstructive

The effect of different meditation styles on the brain

There’s an increasing acceptance in the scientific community that meditation can increase well-being in part through its ability to alter brain functioning. But the way meditation does this differs relative to meditation style.


Before we go into the functional differences that distinguish meditation styles let's quickly outline a method used in neuroscience to measure brain activity... 


Measuring brain activity using neural oscillations

Part of the way the brain communicates is electrical- when a brain cell, in this case a neuron, is activated its electrical potential changes. Brain cells that are situated close together can activate together as a population. When this happens they only activate for a short time, they can then cycle between states of activate to silent and back to activate. This is called an oscillation. The number of activations per second is the frequency of the oscillation. A frequency of 1 Hertz (Hz) is 1 oscillation a second; so 20 oscillations per second is 20 Hz. For simplicity, these brain frequencies have been classified into different bands, which can be measured from the scalp using an electroencephalogram (EEG).

1.     Delta (1-4 Hz)
2.     Theta (4-8 Hz)
3.     Alpha (8-12 Hz)
4.     Beta 1 (12-30 Hz)
5.     Beta 2 (20-30 Hz)
6.     Gamma (30-50 Hz)


Researcher have discovered that different meditation styles induce neural oscillations at different frequencies [3]. The types meditation styles that the researchers examined were:


  • Focused attention
  • Open monitoring 
  • Self transcending 


Lets briefly look at each and the brain how they differ according to brain activity and mental processing

Focused attention
(e.g. Zen-3rd Ventricle, Diamond Way Buddhism, and Loving Kindness)
During this type of meditation a practitioner focuses on a single object such as the breath, an area of the body, or a conceptual feeling (e.g., loving kindness). When the mind wanders the attention is brought back to the task at hand. So the meditator is controlling what’s being attended to. As mentioned in a previous blog entry, this type of meditation cultivates a sense of non-reactiveness. Specifically, with practice a meditator become less reactive when they realise that the mind has wondered. As a result, the practitioner becomes more efficient at returning their attention to the object of focus. Focused attention meditation is associated with increased activity in the beta2 and gamma frequency range.

Beta 2
Beta2 has been reported during focused attention. Thus, it appears to be associated with focusing attention towards a concept.

Gamma
This is the frequency most often associated with conscious awareness. It is thought to bind the myriad of aspects that make up a single feeling, thought, or sensation, into a unified whole.

During meditation these two frequency bands appear to act together to orientate, or focus, attention towards a single object that is then consciously perceived.

Open monitoring
(e.g., Vipassana, Zen, Sahaja Yoga, and Concentrative Qigong)

Open monitoring meditation involves non-reactive monitoring of thought patterns and emotions. So unlike focused attention, the mind is left to its own devices and is simply witnessed. Typically, a practitioner will start with focused attention and then progress to open monitoring. That’s not to say that open monitoring is more advanced or better than focused attention. It just seems that the practice of focused attention can precipitate open monitoring. I wonder if the non-reactiveness that is induced during the practice of focused attention cultivates a sense of acceptance that allows an individual to simply watch the mind without being drawn into the thoughts or feelings. Open monitoring is associated with increased activity in the theta frequency band within frontal midline areas.

Theta
In a review article published last year it was noted that frontal midline theta is most often observed during tasks that involve sustained, internally directed brain activity without external stimuli or responses [4]. This is, indeed, inline with open monitoring where the focus of attention is not a sensation or single thought but instead a more global awareness of the natural state of the mind.

Automatic self-transcending
(Transcendental meditation, and Qigong)
Automatic self transcendence is characterised by the absence of both focused and controlled effort. To begin the meditator concentrates on a mantra or sound. However, the goal of this mediation, unlike focused attention, is not to concentrate on the mantra throughout the practice. Instead focus on the mantra is used to calm the mind and then enter into state of thoughtless awareness. Conversely, both focused attention and open monitoring require focus on an object or the natural activity of the mind, which ultimately keeps the mind engaged. Self-transcendence eventuates beyond this sort activity into thoughtless calm and non-reactiveness to sensory information. Consequently, the practitioner is left with no sensory info, or thoughts, to define their experience. At this stage, the only thing left to experience is the essence of the self. Transcendence meditation is associated with increased activity in the alpha band frequency.

Alpha
Alpha predominates during periods of restful wakefulness and decreases during periods of sensory stimulation. Because of this, it has been described as the brains idling response. Furthermore, alpha is thought to inhibit irrelevant brain activity; increase in alpha are associated with a decrease in visual and sensory perception [5]. Thus, its also been called the brain's inhibitory rhythm. This ties in well with self-transcending meditation as it reveals that during practice the meditator can enter into a brain state that aids in inhibition of spontaneous thought or sensory awareness.



Overall, different forms of meditation are characterised by distinct brain activity. With regards to mindfulness, it has been argued that attention towards a single object (focused attention) or the nature of the mind (open monitoring) both share a mindful quality. During these forms of mediation the practitioner is in a state of focus that keeps attention within the mind. The term mindfulness is therefore very broad and covers a large range of mediation styles some with very distinct brain activity.

But, meditation isn’t always mindful, specifically some styles of meditation are characterised by awareness not associated with thoughts or sensory input. Now, this, is quite something. Can you imagine just a moment where you’re not attending to any sensory information or thinking? It almost seems impossible not to be in this constant state of flux. But research has shown that there is inhibitory brain activity associated with stilling of the mind. Phenomenologically, we glimpse aspects of this sort of brain processing daily. With regards to sensory information, we are constantly ignoring incoming information. For example, we’re not always aware of the feeling of our clothes on our skin, or the ring or watch that we are wearing, unless we pay attention. Furthermore, even if your mind is racing with thoughts there are moments where there are small gaps between thoughts where there is brief stillness. With practice we can withdraw our attention from this sensory flux and extend the moments between thoughts. The only thing left is consciousness...

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 References:

1.         Chiesa, A., The difficulty of defining mindfulness: current thought and critical issues.  Mindfulness, 2013. 4: p. 255-268.
2.         Chiesa, A. and P. Malinowski, Mindfulness-based approaches; and they all the same? Journal of Clinical Psychology, 2011. 67(4): p. 404-24.
3.         Travis, F. and J. Shear, Focused attention, open monitoring and automatic self-transcending: Categories to organize meditations from Vedic, Buddhist and Chinese traditions. Consciousness and Cognition, 2010. 19: p. 1110-1118.
4.         Hsieh, L.T. and C. Ranganath, Frontal midline theta oscillations during working memory maintenance and episodic encoding and retrieval. Neuroimage, 2014. 85: p. 721-729.
5.         Ruhnau, P., A. Hauswald, and N. Weisz, Investigating ongoing brain oscillations and their influence on conscious perception – network states and the window to consciousness. Front Psychol, 2014. 5(1230): p. doi: 10.3389/fpsyg.2014.01230.

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