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...
...................
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.
