April 14

Your brain waves on Transcendental Meditation

[En español]

My interest in Transcendental Meditation (colloquially, and hereafter, known as “TM”), is personal. I learned TM at the very end of my first year as a graduate student, and I joke that it saved my life, but it may not be too much of an exaggeration; beginning to meditate set the groundwork for many changes in my life and I know remains instrumental in my choices. I’ve convinced several people I love to try TM, and failed to convince many more.  I once shared with a fellow meditate-er, in a discussion of the differences between various types of meditation, that I suspected each type mimics a restorative brain pattern, like a different stage of sleep. This article sets out to explore some of the literature on TM and how it might be restorative because – the curse of a being a neuroscientist – it’s not enough to experience the positive effects of TM, I need to know what’s happening in my brain when I meditate and how it “works”.

 

Transcendental Meditation sounds pretty hokey, what is it really?

TM is a type of meditation aimed not at achieving enlightenment or nirvana, but rather at improving quality of life. The meditation practice  is accompanied by a host of physiological changes that begin in the first minute of practice[1] and has demonstrated value in improving everything from hypertension[2to insomnia[3]. It has been particularly effective for relatively intractable conditions such as PTSD in veterans. The technique, practiced twice daily for 20 minutes, begins with repetition of a personal mantra which  “…allows your mind to easily settle inward, through quieter levels of thought, until you experience the most silent and peaceful level of your own awareness — pure consciousness.” What consciousness is and where it is centered are the matter of some debate, but if we accept the brain activity during TM as “pure consciousness” for the sake of argument, we’ll  explore which brain areas are involved, and how.

 

Your brain on TM

TM has been likened to holding the brain in the pattern of activity that occurs just as you fall asleep (“sleep onset”)[4]. During sleep onset, the prefrontal cortex, the center of control in the brain, activates the thalamic reticular nucleus (TRN). This specialized structure is highly connected to various nuclei in the thalamus and makes widespread connections in the cortex (and is, in my opinion, one of the most interesting parts of the brain). The neurons of the TRN, which form a mantle between the thalamus and cortex, are largely inhibitory (meaning they have a dampening effect on neuronal activity). The reciprocal connections between inhibitory neurons of TRN and the excitatory neurons of the cortex are integrally involved in global changes in brain activity, such as those occurring during sleep. Because of this, the TRN is uniquely positioned to coordinate brain oscillations across various parts of the brain[5]. Deficits  in the this area have recently been in implicated in a variety of developmental disorders[6]. The activation of the TRN during TM practice is likely responsible for the initiation of the cascade of effects, physiological and otherwise, that occur while meditating.

TRN_snip

During TM, the two primary brain wave patterns observed are: theta burts and alpha coherence. Theta waves are a relatively slow (~6-10 Hz) and are commonly associated with waking activity and REM sleep. While continuous low-voltage theta waves are present in the early stages of the sleep cycle, and in other forms of meditation (more on this in the next section), during meditation, TM practitioners reportedly exhibit short theta “bursts” that differ in amplitude and characteristic from  low-voltage waves. The theta bursts persist during relaxed wakefulness and early stages of the sleep cycle[7]. It is possible that TM stem causes this increase in theta bursts, and that the increase is related to some of the positive effects resulting from TM. Alternatively, or perhaps additively, an observed increase in alpha1 (8-10 Hz, on the lower end of the alpha range: ~8-15 Hz) power and coherence during TM, might account for the technique’s efficacy. Alpha waves are also present in REM sleep, and have been suggested to occur during moments of insight[8].

Another finding from studies of TM practitioners is increased activation of the default mode network (DMN), or “task-negative network” during TM. This is a group of related brain structures which are de-activated during many attentional tasks, active during brain “idling” and show a paucity of activity in Alzheimer’s Disease. Increased activity in the DMN while practicing TM “suggests that the experience gained during this meditation may be one of greatly reduced cognitive load and heightened sense-of-self[9].”

Default_Mode_Network_Connectivity.png

 

So is this what happens in the brain during the practice of all types of meditation?

In short, no. There are a number of studies on various types of meditation and their relative benefits that I’ll leave for your personal exploration, or a future NeuWrite post. Generally, the literature agrees on three categories of meditation: focused attention (e.g. “loving-kindness-compassion”), characterized by beta and gamma brain waves, open monitoring (e.g. Mindfulness/Zen), characterized by theta waves, and automatic self-transcending (e.g. TM), primarily characterized by alpha1 waves[9]

The CEO of the David Lynch Foundation, a foundation that aims to bring TM to schools, as well as veterans, homeless and other “at risk” groups, describes the differences between these types of meditation using the ocean analogy familiar to many TM-ers: “An agitated mind [] is like 30-foot surges at the surface of the ocean. Focused awareness tries to stop the waves at the top [] while open monitoring tries to observe them until they go away. TM on the other hand, [] has its practitioners plunge deep below the waves, to a quieter depth that’s perfectly still, and blissful.”

Ocean_waves

 

The takeway

Our brains are plastic. By training them  in various ways, through meditation, altered thinking, exercise, etc. it is possible to effect long-term changes in the connectivity or activity patterns in our minds, a concept that has always fascinated me. There are many kinds of meditation and ways to practice. Some are free to try and learn. If TM isn’t for you, there are many other ways to alter your brain waves, and many resources to help you, if you so choose. For me, TM has been transformative and invaluable, less for the moments of peaceful relaxation (wonderful in their own right), than for the ever growing awareness of my own needs and limitations, which informs how I respond to various situations in a deeper sense. Where I once agonized over small decisions, my experience now is commonly that decisions are being discovered, rather than chosen.

As a scientist and a skeptic about even the most basic truths, I had my doubts about this weird tool recommended by my hippy father, but I have no regrets. Learning TM is one of the most worthwhile things I ever did for myself. While I don’t endorse everything the TM organization says (I need more studies controlling for societal differences in child-rearing before I buy into gendered differences in the physical structure of the brain), I do endorse this statement of theirs: “The TM technique’s effectiveness is the same whether you believe it will work or are completely skeptical.” While more work needs to be done to fully understand the process, for now, you and I both have a better idea of how and why it works.

 

References:

  1. Travis F and Wallace RK (1999). Autonomic and EEG patterns during eyes-closed rest and transcendental meditation (TM) practice: A Basis for a Neural Model of TM Practice. Consciousness and Cognition.
  2. Bai Z, Chang J, Chen C, Li P, Yang K and Chi I (2015). Investigating the effect of transcendental meditation on blood pressure: a systematic review and meta-analysis. Journal of Human Hypertension.
  3. Rosenthal JZ, Grosswald S, Ross R, Rosenthal N (2011). Effects of transcendental meditation in veterans of Operation Enduring Freedom and Operation Iraqi Freedom Ywith Posttraumatic Stress Disorder: A pilot study. Military Medicine.
  4. Fenwick PBC, Donaldson S, Gillis PL, Bushman J, Perry I, Tilsley C, Serafinowicz H (2014). Metabolic and EEG changes during transcendental meditation: an explanation. Biological Psychology.
  5. Giradeau G, Benchenane K, Wiener SI, Buzaki G and Zugaro MB (2009). Selective suppression of hippocampal ripples impairs spatial memory. Nature Neuroscience.
  6. Wells MF, Wimmer RD, Schmitt I, Guoping F and Halassa MM (2016). Thalamic reticuarl impairment underlies attention deficit in Ptchd1Y/- Nature.
  7. Hebert R, Lehmann D (1977). Theta bursts: an EEG pattern in normal subjects practicing transcendental meditation technique. Electrocephalography and ClinicaIl Neurophysiology.
  8. Kounios J, Beeman M (2014). The Aha! Moment: The Cognitive Neuroscience of Insight. Annu Rev Psychol.
  9. Travis F, Shear J (2010). Focused attention, open monitoring and automatic self-transcending: categories to organize meditations from Vedic, Buddhist and Chinese traditions. Consciousness and Cognition.
  10. Walton, AG. “Transcendental Meditation Makes a Comeback, With The Aim Of Giving Back” Forbes. http://www.forbes.com/sites/alicegwalton/2015/04/27/transcendental-meditation-makes-a-comeback-with-the-aim-of-giving-back/#62171ddd7ffc
Advertisements