Spindles

EEG spindles are well known in neuroscience as occurring in the early stages of sleep. My research shows that spindles also occur in jhāna meditation and correspond to disruption of the brain’s sensory-consciousness attention networks brought on as meditators direct attention inward to the breath while remaining fully alert. The EEG recording and enlarged extract in Figure 33 from the book, reproduced below, shows the characteristic wave-packet appearance of spindles (highlighted in yellow for clarity).

Video Clip 1

Infraslow Waves (ISWs)

While spindles were observed to some degree for most of the meditators in the study, the next most common feature of strong, rhythmic, slow brain waves was observed in only about half of the cohort of twenty-nine. These slow waves were significantly slower and more rhythmic than other examples seen in neuroscience research, and were classified as infraslow waves (ISWs).

Five of these meditators recorded ISWs of very high intensity, unprecedented in EEG neuroscience studies, which were interpreted as most likely related to energy freed as meditators disengage from the demands of supporting sensory consciousness towards the higher jhānas.

Figures 42 (Figure 35 in the book) and 43 show how ISWs can develop as a meditator gains experience—in this case over an interval of three years (2014 to 2017). This can be seen most clearly in the inset intensity maps corresponding to the start and end points of the individual slow waves highlighted yellow. The intensity maps show how activity is distributed throughout the brain. Note how the focused “hot spot” near or just posterior to the crown of the head (vertex) in the 2014 recording becomes almost entirely dominant in the 2017 recording, indicating increasing proficiency with jhāna meditation over the course of years of practice.

This is illustrated in another form by the 3D cortical maps of Figures 37 and 44a, again reproduced from the book. The nine plots of Figure 37 show the mean underlying cortical sources of brain activity from seven independent EEG recordings (2014–2017) of the five meditators mentioned above who showed the clearest and strongest examples of ISWs. The middle three plots of Figure 37 show that a mean 44.4% of brain activity was focused at the vertex, which can be compared to the greater-than-95% focus at the vertex for subject 5 of this group in the lower panel, Figure 44a. (This figure is based on the detailed quantitative analysis described in the book, summarized in Table 4, chapter 12.) The overwhelming dominance of vertex activity in subject 5—as opposed to the more distributed brain activity indicative of ordinary sensory consciousness—is entirely consistent with Buddhist understandings of the fourth rūpa jhāna, in which the meditator reaches total equanimity and a complete withdrawal from ordinary sensory consciousness. As a group, the five subjects represent around 25% of the total group studied and are believed from the overall evidence to be at various stages of developing the second, third, and fourth rūpa jhānas.

Cross section (sagittal) view of the brain

 
The cross-section (sagittal) view of the brain (Fig. 44a) shows the position of the vertex source. The vertex area of the brain is highly connected to core regions of the brain and upper brain stem, which in turn are highly connected to the nervous systems of the body.

Video clip 2 shows a portion of the original EEG recording from which the segment in Figure 43 and the 3D plots of Figure 44a are derived.

Video Clip 2

Responsiveness to willed intention

The concept of brain plasticity is often used in neuroscience to describe the ability of the brain to adapt to different conditions or to recover from injury. This study of jhāna meditation has revealed a property closely related to brain plasticity, which is the remarkable responsiveness of the brain to the willed intentions of a meditator. Figure 36 from the book is one among several examples. This meditator is beginning a practice with the direct intention of developing the higher jhānas immediately, without attending to a preliminary progression through lower stages. Within less than 40 seconds, very strong and extensive slow waves have developed, initially in the form of strong inhibitions. 

Video clip 3 shows live sequences from the original EEG recordings of this Bu Ddho practice..

Video Clip 3

Pīti: Deliberate Arousal of High-Energy States

Related to the above are techniques in esoteric Buddhism to deliberately develop high-energy states, which are then equally deliberately calmed into deep tranquillity and jhānic absorption. At their most intense, such practices can resemble grand mal seizures in terms of brain activity, yet practitioners experience no discomfort and can arouse and calm the states at will. These techniques date back to the early years of Buddhism, and perhaps even earlier, and are found both in Tibetan yoga (in the form of practices such as Tummo, or inner fire) and within the Yogāvacara practices of Southeast Asia described in Jhāna Consciousness. From a modern, scientific perspective, these practices are of great interest in relation to epilepsy, raising questions as to whether any aspects of these techniques might be adapted to mitigate the intensity or frequency of epileptic seizures.

Figure 39 from the book was recorded in 2018 with the consent of an experienced meditator. The segment highlighted in yellow and enlarged in the lower panel shows the most intense part of the episode, which is localized in the posterior temporal region of the brain. 

Video clip 4, from the original EEG recording, shows the episode unfolding in real time.

Video Clip 4