The first experience I’d like to discuss is the separation of awareness from action that is necessary in order to practice breath meditation. In this technique, the aim is to observe the natural flow of the breath without exerting any influence on it whatsoever. However, as one soon finds, this is exceptionally difficult since the brain seems to be predisposed to control the breath whenever attention is directed to it. This is perhaps evidence in support of Schopenhauer’s claim that the intellect is enslaved by the will, where our conscious mind only directs itself to sense objects that are of importance to our aims and desires, and where whatever is apprehended consciously becomes subject to top-down control. The dissociation emerges eventually as one learns to just observe, thus building a bridge between the high-level conscious brain states and lower level autonomic regulatory body functions. Thinking back to my neuroanatomy class, I remembered that the vagus nerve in the medulla is responsible for the parasympathetic control of breathing, meaning that it exerts a slowing effect on the breath. Therefore, the moment that the top-down control of breathing is suspended, the vagus begins to take over and this explains the slowing of the breath that occurs during concentrated meditations. The vagus also has a sensory component, so perhaps paying attention to the breathing involves the spreading of consciousness to the vagal element of breath, amplifying both sensory and motor visceral functions. The spreading of consciousness may involve the hooking up of brainstem neurons into the workspace architecture of the cortex through the bidirectional links that flow through the reticular formation. The inhibition of the conscious control of breathing may involve the weakening of the connections from specifically prefrontal cortical regions involved in executive control to the diaphragm via the corticospinal tract, possibly through inhibitory interneurons in the brainstem reticular formation as the tract descends through it.

Regarding the brainstem, I had a distinct feeling of lowering the overall activation of the brain, bringing me down to a lower wavelength, which I could only do in my moments of solid concentration. I situated this experience in the brainstem for two reasons: a) the reticular formation is known to be an overall cortical gain modulator through its non-specific input into all layers of the cortex via the thalamus, and b) the seeming involvement of the brainstem reticular formation in the other aspects of the meditation as I mentioned in the previous paragraph.

This dissociation between consciousness and action also appears during the vipassana meditation phase where we are instructed to pay attention to the sensations on the body, some of which are painful, and are told not to react to them. This is extremely difficult at first since the brain’s conditioning impels it to immediately withdraw from painful situations and to act upon the perception of pain. Equanimity is the skill that develops whereby the meditator becomes able to sit and observe the sensation no matter what it may be without reacting. Again, I interpreted this in terms of the spreading of consciousness into the insula that is responsible for the emotional self-awareness of our bodies, in a specifically affective tone. I found that I could detect a slight difference between perceiving my body epicritically, which I took to be mediated by the somatosensory cortex, and protopathically, which I imagined was mediated by the insula. The weakening of the action circuits could be related to the bidirectional links between insula and prefrontal cortex, whereas the spreading of consciousness to this area again reflects the integration of its neurons into the workspace architecture.

Relating to the insula, I drew parallels between the body schema that is typically described in the body representation literature and activity in the insula based on the experience I had of exploring my body ‘from the inside’. This was opposed to exploring the body ‘from the outside’ where I would visualize the form of the body part in question as it typically appears to me externally, and this is what is known as the body image. Feeling the internal structure of the body was a heterogeneous mode of body perception, which could nevertheless be elicited by the visualizing technique, but was faltering and transient when induced in this manner. The alternative was to simply start straight from the internal feeling of the body, a sense that I did not have access to before I started meditating. I interpreted this again as being due to the spreading of consciousness to insular regions that previously would have remained unconscious. The externally directed mind of the non-meditator only becomes conscious of activity in somatosensory and visual cortices, perception of the body in which manner corresponds to the body image. Interestingly, I had a very subtle experience of the interaction between the two where feeling the body from the inside could only be properly constructed into the coherent body structure by the superimposition of the body image derived from visualization of the body onto the raw sensations taking place in the insula. In rare moments of complete dissociation between these two, there was a distinct feeling of the loss of the structure of the body and the dissolution into raw sensation without form. As soon as I brought back the body image, through the visualization of its form, the sensations became referred to that structure and a more coherent body representation was developed.  Additionally, I felt that I could observe the recalibration of the mapping between the two that occurs when the body moves slightly. There was a slight time delay as the recalibration proceeded to remap the correspondence between the body image and body schema. This seems to imply that the body image is situated in space and is used to locate the body schema spatially, and that when the posture changes, the spatial relationships between the various body parts need to be updated.

Another interesting effect I observed was the laterality of prosody in the brain. Notably, whenever the chanting would start and the melodic voice would begin to lull us into a meditative state, my left lip would begin smiling while my right lip remained unfazed. I interpreted this in terms of the prosodic attunement of the right brain, contrasted with the digital fact-oriented nature of the left linguistic brain. Another laterality effect I observed during the meditation was that my pain was always focused on the right side of my back, whereas my right side always exhibited muscular spasms and clenching. This led me to hypothesize that the consciousness/action dichotomy is instantiated laterally with the right brain responsible for consciousness and the left brain responsible for action. However, this is obviously far too simplistic and naively sketched, but there may be some merit to it.  

I had the hypothesis during the retreat about a potential circuit that brings together a triadic connection between limbic-insula-prefrontal cortices and which is responsible for the unconscious mind. The insula receives afferents from sensory and multisensory cortices after they have been processed by limbic centers for their valence on the basis of benefit or harm to the organism and then a prefrontal circuit reacts on the subsequent body sensation. There seems to be a direct mapping between the sensory representation and the insular activity that is experienced as a body sensation. An example of this is afforded by the sudden loud noise occasioned by a sneeze or a cough while I am in a deep meditation. The moment that the sound is consciously apprehended there is an accompanying body sensation that matches the expected characteristics of the sound, in this instance a feeling that approximates the splash of phlegm onto the part of my body most proximal to the source of the sound. The limbic area that is of primary importance here may be the anterior cingulate since it is responsible for the organism’s drives and hence has to process sensory stimuli on the basis of whether to pursue or flee from them. Also, hippocampal and parahippocampal lobes probably have something to do with this circuit due to their involvement with memory in both its spatial and episodic aspects.

Another thought I had during the retreat was that the vibrations that I hear in the sound of silence emanate from insular activity, since that is also a vibrational experience, the different levels of subtlety of which corresponded to different pitches of the sound. I remember having the experience of being able to select for different levels of subtlety of sensations simply by attending to the various pitches of the sound. I hypothesized that this was due to a direct link between insular and auditory cortex. During my more philosophical contemplations I would find myself wondering whether the sensations that I experienced actually were just neural activity in the insula or if they were the physical structure of the body itself as Goenkaji says. However, these kinds of metaphysical considerations are not very helpful and should not be taken too seriously.

One fascinating experience I had was of sensations in my brain. This struck me as neurally paradoxical if the brain is itself the seat of the sensations. It would lead to a strange circularity unless certain parts of the brain remain immune to sensation. However, as far as I could tell, there was not a single part of the brain that I could not spread my awareness to. Nevertheless, this was one of the faintest parts of the body that I could feel, so this last point is not yet conclusive. I wonder whether what I was feeling was actually just the blood vessels in the brain, especially since I believe the sensations to be occurring in the insula, which is known to be the interoceptive cortex, and hence would naturally be attuned to sensations from the smooth muscles that line the blood vessels of the brain.

A curious effect of the meditation is to cause strange and fascinating hallucinations to occur not unlike those that I experienced on psilocybin mushrooms. The difference between psychedelics and meditation that I thought of was that the former increases temporal lobe activity through its serotonergic stimulation – assuming that the temporal lobe is itself serotonergic – whereas the latter caused the same effect by reducing the interference from distractors through the calming down and quieting of the mind. This is supported by the fact that the hallucinations only occurred when the attention was directed to some perceptual object, the processing of which was heightened due to the availability of larger amounts of resources. That psychedelics act on the temporal lobe is not certain. However, the fact that the serotonin-producing raphe nuclei are located in the brainstem reticular formation is instructive and supports the similarity in the experiences.

This seems to exhaust the list of notable occurrences and correspondences with neuroscience and psychology that I could remember a week after returning from the retreat. It remains for me to give more thought to some of these and to use them to structure my thinking about the various strands of research that I am engaging in here at the UCLA psychology department.