Meditation and brain waves

Fractal illustration of abstract tech background with brain and heart

The brain is an electrical organ. Brain waves are features of the brain’s electrical activity, produced by synchronised electrical pulses from masses of neurons communicating with each other. Different types of brain waves are known to be correlated with different states of consciousness. In this article we look at the existing research on how meditation affects brain waves, and therefore its implications for how it may affect levels of consciousness.

What exactly are brain waves?

In the brain, there are roughly 100,000,000,000 neurons. And contrary to the myth that humans use only a small percentage of the brain, most of these neurons are active and firing most of the time. This creates a serious communication challenge: how to synchronize a staggering number of individual electrical signals across disparate sections of the brain in order to allow for coordinated brain activity.

This is where brain waves come in. Brain waves are simply the features of aggregated brain electrical activity, and they provide a means of coordinating individual electrical signals into a broader pattern.

How Brain Waves Are Measured

When measuring brain waves (via machines such as an EEG or an MEG), the three main components of interest are the frequency, the amplitude, and the phase. Using the analogy of sound waves can help illustrate these three features of brain waves:

  • Frequency refers to the number of impulses over a length of time. In the case of sound waves, a higher frequency means a higher pitch. In the case of brain waves, a higher frequency means a cell more frequently creating electrical impulses.
  • Amplitude refers to the relative intensity of the wave. In the case of sound waves, a higher amplitude means a louder sound. In the case of brain waves, a higher amplitude can mean a greater number of neurons firing together at once.
  • Phase, in this case, refers to the temporal synchrony of different wave forms together. For sound waves, if two waves with different frequencies (different pitches) are “in phase,” this will likely mean that the provide a pleasant, euphonic combination when played together (e.g. a major chord). When two distinct sound waves are out of phase, this could mean discord (e.g. a tritone). For brain waves, being in phase generally means having spikes of activity in synchrony.

By outlining this analogy between sound waves and brain waves, it becomes clear what the function of brain waves is. In order to make harmonius music, a conductor must coordinate the individual voices or instruments to precisely regulate the pitches that are played (frequency), how loud or how soft they play (amplitude), and the arrangements of the different pitches in temporal synchrony (phase).

Similarly, in order for the brain to “orchestrate” signals across a massive number of individual “instruments,” the brain must coordinate individual neurons across disparate brain regions to precisely regulate the rate of speed at which they fire (frequency), how many neurons in a given region fire at once (amplitude), and the synchrony with which different ensembles of neurons fire together (phase).

The Different Types of Brain Waves

With this understanding of how brain waves are measured and how the brain uses them to coordinate the electrical activity of neurons, it becomes much easier to understand the different types of brain waves that scientists have identified.

Each type of brain wave has its own characteristic pattern of activity, defined by idiosyncrasies in frequency, amplitude, and phase, among other features (e.g. location). However, in order to simplify, it’s possible to categorize them primarily by frequency – roughly speaking, how fast or slow the waves are.

In the same way that musical notes that have different frequencies are given different letters in the Latin alphabet (e.g. a C major chord is C-E-G), brain waves have been given different letters in the Greek Alphabet. The four most well-studied and well-known are Alpha, Beta, Delta, and Theta waves. Let’s take a brief look at each type of brain wave individually:

  • Beta Waves represent normal waking consciousness. When the brain’s electrical activity is measured during periods of strong mental engagement, the resulting brain waves contain a characteristic pattern of high frequency (15-40 cycles per second), low amplitude wave forms.

BETA

  • Alpha Waves represent wakeful relaxation. When an individual experiences a resting state, such as sitting down after physical activity or taking a peaceful walk in nature, they are likely activating these lower frequency (9-14 cycles per second), higher-amplitude wave forms.

ALPHA

  • Theta Waves could be considered the “zoning out” brain waves. Activities like day-dreaming, running outdoors, long stretches of highway driving, and any other automatic, “thoughtless” activity likely induces a pleasant mental state of free ideation that corresponds to brain waves that are of a lower frequency (5-8 cycles per second) and a higher amplitude than alpha waves.

THETA

  • Delta Waves are most commonly associated with deep sleep. Each night, as we descend from wakefulness to deep, dreamless sleep, our brain waves steadily decrease in frequency (down to between 1.5-4 cycles per second) and increase in amplitude. The frequency of delta waves – the lowest of all brain waves – is what gives this stage of sleep its name: “slow-wave” sleep.

DELTA

(images from Scientific American)

These four brain waves are well-known, and every individual moves up and down through these higher and lower frequency brain waves each day and especially each night, while they sleep.

In addition, a newer, less well-understood type of brain wave has also become implicated in meditation research.

  • Gamma Waves are a rather mysterious wave form that are currently receiving great interest from researchers. Gamma waves define the highest frequency brain waves (from 30-80 cycles per second), and are highly implicated with characteristically “human” activities including perception, attention, working memory, and learning. [1]

With this understanding of the different types of brain waves and their basic functions, let’s take a look at some of the recent research into how meditation affects brain waves.

 

How Meditation Affects Brain Waves

Several recent research studies have explored the relationship between meditation and brain waves. In one study, performed jointly by researchers in Australia and Norway [2], participants were prompted to alternate between performing nondirective meditation and resting with their eyes closed. Meanwhile, their brain waves were measured.

The researchers found that theta waves – the ‘zoning out’ waves described above – were found most strongly in regions of the brain involved in inward monitoring of experience. When the participants merely rested, without the active process of meditation, the free and relaxed ideation that is marked by theta waves was not present in these internal monitoring areas.

Along these same lines, the researchers also noted that alpha waves – noted above as the ‘wakeful relaxation’ waves – were more abundant during meditation than during rest in the most primordial part of the brain, including parts responsible for basic functions including heart rate and breathing.

Critically, the researchers also found that there was essentially no presence of either beta waves or delta waves during both rest and meditation, indicating that the minds of the participants were engaged in something other than sleep and waking consciousness throughout their experience in wakeful rest and in meditation.

The presence of alpha and theta waves during meditation is important, because it supports the hypothesis that meditation, rather than conventional forms of rest, provides a deep form of relaxation that is different from sleep (delta waves).

 

Another study by researchers in Croatia also measured the brain activity of practitioners of a nondirective meditation technique, Transcendental Meditation [3]. In this case, one of the key differences was that the participants of the study were measured for brain activity before and after a three-month meditation program, in order to illustrate the effects of sustained practice.

Most broadly, the researchers found that after three months of meditation, participants displayed several changes in their brain waves: The left hemisphere of the brain – primarily responsible for language and logical thinking – showed decreased theta wave activity and increased delta wave activity. Participants also showed theta waves that were more in phase in their temporal and occipital lobes, which are primarily responsible for integrating sensory input including visual and auditory stimuli.

It’s very important to note that these changes in brain activity were measured during normal, waking, activity, not during meditation.

After only three months of practicing transcendental meditation, participants showed baseline brain waves indicating greater integration of the sensory areas of the brain, and decreased general anxiety in the thinking centers of the brain.

So we see that changes in brain waves occur not only during mediation, but there are also accumulated benefits of meditation – even after only a few months – that improve brain function during normal waking consciousness.

Of course, the benefits of meditation accumulate still more if an individual dedicates themselves to a lifelong practice. In a final study, researchers led by meditation research pioneer Richie Davidson at the University of Wisconsin performed an analysis of the differences in brain waves between long-term meditators and non-meditators [4].

Specifically, Davidson and his colleagues measured eight Buddhist practitioners who had each spent between 10,000 and 50,000 hours meditating in the same traditions, over the course of 15-40 years. The brain activity of these subjects during meditation was compared to comparable activity of ten individuals with no experience meditating.

The biggest and most amazing difference that Davidson and his colleagues demonstrated in the brain waves of long term meditators was the ability of the lifelong practitioners to rapidly engage in long-distance gamma synchrony.

In meditative states lasting less than 1 minute, the long-term meditators were able to activate gamma waves across huge distributions of neurons, reflecting a state of neural synchronization across a variety of different parts of the brain.

Different Meditative States Correlate to Different Brain Waves

It’s important to note that the studies described above differed slightly on the type of meditation that the participants employed. While the science on how different meditative states correlate to different patterns of brain activity is very new and not yet entirely conclusive, a few patterns have begun to emerge.

For example, the studies outlined above support a difference arising between the presence of gamma waves in nondirective vs. concentrative meditation.

Nondirective meditation, also referred to as effortless meditation or dhyana, is commonly referred to as a state of “no mind.” 

This refers, most generally, to a practice of focusing on one’s breathing or on a meditative sound, but at the same time giving the mind license to wander beyond this point of concentration.

This is contrasted by what is sometimes termed concentrative meditation, in which the practitioner focuses their attention specifically on their breathing, on a specific thought or wish, and purposefully suppresses other thoughts in order to maintain their focus.

In the first two studies outlined above [2-3], the participants were instructed to perform nondirective forms of meditation, and there was no presence of gamma waves noted.

In the third study [4], however, which focused exclusively on the presence of gamma waves, the long-term practitioners had generally been engaged in a more focused loving kindness meditation that could likely be considered to be more concentrative than nondirective. The researchers reported that practitioners would often focus their loving kindness meditation on the figure of a single individual, for example.

In fact, even more to the point, the researchers in this study specifically mentioned that there is likely to be differences in brain waves due to the fact that their practitioners were performing a concentrative type of meditation, and even went so far as to state that “future research is required to characterize the nature of the differences [in brain function] among types of meditation” (16372).

Fortunately, one recent study headed by a team of researchers in Germany specifically investigated this very question, analyzing the differences in brain waves between distinct meditative states [5].

Specifically, the researchers recorded brain activity of thirty long-term meditators – with at least 5 years and 1000 hours of experience – while performing meditative tasks including thoughtful emptiness, focused attention, open monitoring, among several others – all these compared to a simple resting state.

Considering the categories mentioned above, for our purposes we may consider the researchers’ designation of a state of “thoughtful emptiness” to represent nondirective meditation, and the “focused attention” meditative task to represent concentrative meditation.

The researchers found that a state of thoughtful emptiness showed much lower levels of activity in the regions of the brain responsible for thought, cognition, and language processing than the focused attention task.

While in a state of thoughtless emptiness, the alpha and beta waves of the participants were also of a much lower amplitude than a state of open monitoring, indicating deeper relaxation.

At the same time, however, the researchers demonstrated that meditating in a state of thoughtful emptiness also prompted significantly fewer delta and theta waves than the state of rest with closed eyes, indicating that the practitioners were not experiencing sleep or drowsiness while in the state of thoughtless emptiness.

 

Conclusion

The research is nascent, but sufficient correlation has been shown to warrant further research on the topic, and understand more robust connections, and eventually causality, of how meditation affects brain waves.

 

 

References

[1] Jia, X., & Kohn, A. (2011). Gamma rhythms in the brain. PLoS Biol, 9(4), e1001045. DOI: 10.1371/journal.pbio.1001045

[2] Lagopoulos, J., Xu, J., Rasmussen, I., Vik, A., Malhi, G. S., Eliassen, C. F., … & Davanger, S. (2009). Increased theta and alpha EEG activity during nondirective meditation. The Journal of Alternative and Complementary Medicine, 15(11), 1187-1192. DOI: 10.1089=acm.2009.0113

[3] Tomljenović, H., Begić, D., & Maštrović, Z. (2016). Changes in trait brainwave power and coherence, state and trait anxiety after three-month transcendental meditation (TM) practice. Psychiatria Danubina, 28(1), 63-72. PMID: 26938824

[4] 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 America, 101(46), 16369-16373. DOI: 10.1073/pnas.0407401101

[5] Hinterberger, T., Schmidt, S., Kamei, T., & Walach, H. (2014). Decreased electrophysiological activity represents the conscious state of emptiness in meditation. Frontiers in Psychology, 5, 99. DOI: 10.3389/fpsyg.2014.00099

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