Over 40 years ago during the time of the first Samatha meditation classes in London and Cambridge, Nai Boonman suggested we might someday carry out research into the effects of meditation on the brain. At that time, electroencephalograph (EEG) equipment was extremely expensive, and would probably have filled a small room. Since then technology has advanced enormously, and prices fortunately have dropped. Last year we acquired a 19-channel EEG system and the first recordings of Samatha meditators in this tradition were made during an intensive retreat at the Samatha Trust’s National Centre in Wales, during August 2010. Further recordings have been made since then at the Manchester Centre, and in London, and another set of recordings will be made during August 2011.

Over the last 30 years there have been many EEG studies of meditation, but most of these have been of more open relaxation modes of practice, with very few studies of focused meditation, or Samatha, comparable to our own tradition. Notable exceptions have been a study of Zen masters as long ago as 1966, a few studies of highly experienced Tibetan meditators since 2001, and a recent (2010) study of a group of monks from Achaan Cha’s forest tradition based in Italy (that study, however, used fMRI rather than EEG).

The protocol so far has been to record a meditator’s EEG for periods of about 15 mins as they practice rupa and arupa jhana, as well as the deliberate arousing of energy, or piti, sometimes fondly referred to as “psychic-power” practice. 19 electrodes are positioned on the head according to the international system that allows different EEG studies to be compared, overlying the frontal, temporal, parietal and occipital regions of the brain. Signals are relayed to an EEG amplifier and laptop analysis system.

What is described in the following is very provisional – it will take time and many more recordings before we can start to understand in more detail the effects of meditation on the brain – they are offered here at this early stage to give a taste of what is being seen so far. Individual meditators’ identities are not disclosed.

Rupa / Arupa Jhana

Meditator A

Rupa Jhana

Each electrical trace on the left is from an electrode pair on the meditator’s head. The 2-dimensional plots on the right show the intensity maps looking down on the head, and from the side, for the two low-frequency bands Delta (1.0 –4.0 Hz) and Theta (4.0–8.0 Hz). For this meditator, activity is focused in the left frontal cortex, in the Theta band (4.0–8.0 Hz), known to be associated with deep relaxation. (Higher frequency, Alpha and Beta, activity is not shown as it is effectively suppressed during deep meditation). In “normal” daily activity, Theta waves are overshadowed by higher frequency Alpha and Beta waves, and Theta activity tends to come more at the borders of sleep. In meditation, however, Theta activity develops as part of a highly alert state, and this meditator was giving attention to a strong visual mental image, nimitta.

Arupa Jhana

After this meditator moved into developing arupa jhana, letting go of attending to the nimitta, electrical brain activity shifted to the right parietal lobe, which, among other functions, is known to be involved in integrating spatial representations. The intense energisation has now spread into the low-frequency (0–4 Hz) Delta band, as well as the Theta band. Delta activity is normally mostly found in deep sleep, but here it occurs as part of the highly aware meditative state. This meditator acknowledged being at a fairly early stage in developing arupa jhana, but was highly encouraged to see the dramatic change in moving from rupa jhana to arupa jhana practice.

Meditator B

Arupa Jhana

This example shows the arupa jhana practice of a very experienced meditator. The raw electrical signals on the left show highly synchronised activity (top to bottom traces) across large areas of the brain. The plots on the right confirm this, and show very large areas of the brain across frontal, parietal and rear occipital areas to be highly energised. The frequency range is strongest in the Theta band, but the lower frequency Delta band is also strongly energised. These two arupa jhana examples suggest Delta-band very deep “relaxation” – or in our terminology “absorption” – develops in arupa jhana, in an active form, unlike its more normal occurrence in deep sleep.

Energisation / Piti / “Psychic Power” Practice

Meditator C

Below is an historic picture – the first recording of an experienced meditator demonstrating the deliberate arousing of a high-energisation state, or piti, often referred to as “psychic power” practice. The surprise on seeing this was to notice the similarity to EEG recordings of some epileptic seizures, although in this case under complete control in entering and leaving that state, and with no discomfort.

A big problem in analysing a recording such as this, is to separate the movement or muscle artifacts from the actual brain EEG activity.

A second recording (of Meditator D) shows a milder arousing of energy where the separation of physical and muscle artifacts is a little easier, though still not straightforward. This meditator had been practising this formal energisation practice for only a relatively short time, but had previous experience of developing piti in other ways.

Meditator D

Notice how the meditation practice is intensified after the “psychic-power” burst, compared to the signals just before, illustrating the power of this technique as a “short-cut” into deeper levels of absorption (an example of the tranquilisation, passaddhi, of piti, as a prelude to samadhi). The plots to the right are from the “after” portion, and for this meditator show intense activity in two areas, in the Theta band.

Comments

The recordings so far show differences between meditators’ brain activity, even though ostensibly practicing the same state of meditation, and it is interesting to follow this up after recordings by careful debriefing of meditators as to their subjective experiences (recollection), and the subtly different ways each person interprets and formulates the jhanas. However, there are features in common. The main finding is the relative ease with which Samatha meditators are able to develop states of deep relaxation, with slow EEG activity normally only seen in deep sleep, or on the boundaries of sleep. Delta wave activity indicates very deep relaxation, but the meditative state is highly alert as opposed to deep sleep. Theta wave activity is known to enhance unconscious integration of ideas, and is related to creativity, which in meditation terms could be seen as related to the arising of insight following Samatha meditation.

A second finding is the ability of some experienced meditators to self-induce states of high energisation similar to epileptic seizures. However, unlike epileptic seizures, when developed as part of meditation practice, the “seizure” is under full control with no discomfort. This raises the intriguing question, that if a meditator is able to develop this skill, are there aspects of Samatha meditation practice that could usefully be applied to help epilepsy sufferers better manage their seizures, and ideally reduce their propensity to seizures. Over the years there have been conflicting views on whether meditation could benefit epilepsy sufferers, and there are very few useful studies so far. Some suggest meditation might actually provoke seizures, while others believe it might help reduce them. An email survey of all our current Samatha practitioners (over 300), including all our Samatha teachers (who have taught many more individuals over the last 40 years), has not brought to light even a single occurrence of an epileptic seizure proper being triggered by Samatha practice.

A hypothesis would be that this particular tradition of Samatha is very effective in carefully developing attention (vitakka/vicara), and the ability to choose whether or not to respond to sensory stimuli. This, together with the deep relaxation and integrative effects of Delta wave activity is likely to be the basis for what we are seeing so far, and the capacity of meditators to sustain highly energised and synchronous brain electrical activity without loss of control.

Future Directions

To deepen the study, meditators will need to be recorded both during meditation, and outside meditation for comparison of brain activity. We also would like to look at beginner meditators, as well as those more experienced, and those highly experienced. This will need more organisation, and the establishment of a core group for recording EEG, and for analysis. Enquiries are welcome from Samatha meditators with the following interests/skills:

Computer programming skills since there will be a need to customise software packages – front-end driver skills, knowledge of MatLab etc.
An interest in reading up on the neurology of the brain – the functions of different regions etc.
An interest in bridging the disciplines of meditation/spirituality, neurology, and mental health.

The results so far have aroused interest from researchers in other fields, such as epilepsy, sleep studies, general health and well-being, as well as mental health, and for consciousness studies generally. To develop the study further, towards publishing results in peer-reviewed journals, we urgently need to upgrade the EEG equipment used so far, and would like to invite financial donations to help with that. The current equipment is a relatively inexpensive 19-channel system that has produced very useful results, but it has limitations. In particular, it is limited to a recording frequency range of only 0.5 to 30 Hz. To explore in more depth how perception and consciousness actually develop in relation to focused meditation states, higher frequency coverage is needed, as has been used in some studies of Tibetan meditators. More sophisticated software is also needed. We would also like to extend the study to see how the meditation state is affected by sound and visual stimuli – so-called event-related potential (ERP) studies. ERP studies potentially throw light on the more subtle processes of perception and how different brain areas are activated either sequentially or in parallel. This, combined with the unique ability of Samatha meditators to give detailed subjective feedback of their actual experience, has great potential for consciousness studies. The more advanced equipment we need will cost in the region of £10,000 and would allow 24 or 32 channels to be recorded over a frequency range 0–150 Hz.

For further information, and particularly if you would like to know how to make a financial donation to this study, please contact Paul Dennison at This e-mail address is being protected from spambots, you need JavaScript enabled to view it

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