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| Katherine MacLean |
The talk focused on studies where i have been subject and collaborator: the Jud Brewer/Yale experienced meditators work "Meditation Experience is Associated With Differences in Default Mode Network Activity and Connectivity" , Jeffery Martin's Ph.D. thesis "Ego Development Stage Does Not Predict Persistent Non-Symbolic Experience", and the Institute of Noetic Sciences study "Electrocortical Activity Prior to Unpredictable Stimulii in Meditators and Non-Meditators".
The magic mushroom work "Neural Correlates of the Psychedelic State as Determined by fMRI Studies With Psilocybin" by Robin Carhart-Harris/Imperial College, London was also briefly discussed. As these were all blogged here earlier, you can delve deeper from these links. There is an excellent video of Robin's talk on his paper on the Multidisciplinary Association for Psychedelic Studies (MAPS) website. Unable to find pic of Robin - many videos - google him.
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| Susan Blackmore |
The room was full of folk, some sitting on the floor, with many questions and discussions afterwards and throughout the week. Jeffery Martin, Susan Blackmore, Robin Carhart-Harris, and his collaborator at Johns Hopkins, Katherine MacLean, and some IONS folks were there. Katherine's work on psilocybin and "open mindedness" was covered by ABC News; there is an excellent interview with her on The Secular Buddhist.
As the Universe would have it, Robin, Katherine and i had many serendipitous opportunities to discuss the cog neuroscience similarities behind how psychedelics and persistent non-dual meditative states "work". IMHO, these are two of the most fertile grounds for cognitive neuroscience research currently as they represent relatively "controlled" situations, if that isn't an oxymoron wrt psychedelics. As it always is with science, every discovery opens another door, often several doors.
There is much exciting work underway on exactly how the different centers are induced to not communicate with each other, and/or how parts of them are "deactivated", or so reduced in functionality, and retained at that level, that their role is not significant. The PCC and mPFC, which have been discussed extensively before in these blogs, receive/consume a disproportionate amount of blood flow/energy compared to other centers. Other parts of these two core centers, apparently, do many tasks in addition to "selfing". How that partitioning occurs, and yet allows the rest of the functions to continue normally, we don't understand, yet.
Robin and Katherine were the plenary speakers in a TSC session "Consciousness and Hallucinogens". Robin's talk was "How do Psychedelics Affect the Brain to Alter Consciousness?"; Katherine's was "Psilocybin and Personality Change - What Do Increases in Openness Tell Us About Potential Mechanisms of Action and Therapeutic Applications?".
The best line of the conference was by one of the psychedelics-effects folks, a wonderfully-talented junior scientist (who will remain unnamed) who proudly, and seriously, announced in his talk that "I was not high when I was conducting the studies with others", which got the most laughs i heard at the conference.
Robin and Katherine are great researchers and a delight to work with. They collaborate with Jud Brewer, the principal investigator on the Yale "experienced meditator" work, who i have worked with extensively this last year. Their willingness to collaborate openly is all too rare in academia; the great hope for cog neuro (and meditation) is that such stellar "young" folk will continue to be attracted to it. It is the "final frontier", perhaps for a long while.
There was a very good, and useful, paper by Patricia Sharp of Bowling Green State University, who the Universe also arranged that i would meet serendipitously at breakfast. Her paper, "Buddhist Enlightenment and the Destruction of Attractor Networks: A Neuroscientific Speculation on the Buddhist Path from Everyday Consciousness to Buddha-Awakening" is "in press" for the Journal of Consciousness Studies. Patricia promised me a copy when it issues.
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| Substantia nigra |
Eventually, however, as we all know, pleasures eventually "saturate" with time as they become familiar. Unfortunately, or fortunately, depending on your viewpoint, as the activities associated with that pleasure are performed repeatedly, they ultimately produce an anticipatory down-regulation/release of dopamine. we are left with mental craving for the pleasure but w/decreased levels of the pleasure-generating "reward" neurotransmitters as our result. So we indulge more and more in the situations that led up to the pleasure in the past, with increased "craving", hoping for more pleasure, but keep receiving less and less pleasure, and so it goes...
The big question is why the great pleasures of "thought-free" meditation, presumably operating by the same dopamine/opiod neurochemistry system, persist, and do not saturate and operate in the same way to produce less pleasure with more craving. Patricia's paper, and Buddhism, develops the idea that our repetitive thought patterns can be viewed as a form of addiction. If we dramatically reduce the internal narrative, the dopamine down-regulation/reduction apparently does not occur. Instead of an endlessly repetitive stream of thoughts, the brain is engaged in a dance of open awareness with its continually changing show, and all of its concomitant neurotransmitter-induced pleasure.
IME, there is more pleasure in thought-free stillness with open eyes rather than with closed eyes, particularly in nature. In Zen meditation, we are often told to keep "Buddha eyes", or eyes that are slightly open, rather than fully closed, or fully open, to just barely engage the "brain"/visual cortex but not more than that. This offers a possible explanation. With the eyes open, and without thoughts, nature, or even just anyplace, is ever fresh, ever changing. This apparently engages the brain in endless variety, pleasure-enhanced with dopamine and opiods.
Gary,
ReplyDeleteThere could be several mechanisms at play in sustaining "persistent blissful awareness" without neurotransmitter burnout (the pleasure/ craving death spiral that you describe). Regular meditation and mindfulness practice may cause:
- a shift from dopamine towards opiods. Burnout appears to be more pronounced with dopamine than opiods. This may explain why advanced practicioners describe a feeling of sustained "relief from pain" (a characteristic of opiods) and equanimity (pleasure from dopamine has a more "jittery" quality). They also report not suffering, even when experiencing physical pain, much as someone might if they were taking an opiod such as morphine.
- increased sensitivity to small quantities of neurotransmitter. Mindfulness creates greater awareness of the feelings generated. In addition, there also may be a reduction in the total number of receptors. The level of well being may depend more on the percentage of receptors that are engaged (creating a sense of fullness/ completeness) rather than the absolute number that are activated.
- greater diversity of neurotransmitters. As you mention, there are multiple types of dopamine receptors. There are also a variety of endogenous opiods and receptors. Furthermore, oxytocin and serotonin, which produce a sense of connectedness and transcendence, are also stimulated by meditation. The jhanas, in particular, are a meditative system which appears to sequentially focus on each of these neurotransmitters, which may contribute to the overall effect.
Traditionally, meditation is said to aid in maintaining mindfulness and also, greater mindfulness can make it easier to meditate. It may be that the way that each approach develops the neurotransmitter system may lead both to "feel better" and therefore support further practice.
It will be interesting to see the Sharp paper when it comes out.
Ron
Some interesting points, Ron. As i recall Patricia's preso, your first idea on a shift from dopamine towards opiods, is in her model as well. Great that you came to the same conclusion.
DeleteThe "increased sensitivity to small quantities" is a little more difficult to see; connecting mindfulness and sensitivity to a reduction in the number of receptors would be unlikely, IMHO. i don't know of any studies that support that, but i don't know all studies.
The "greater diversity of neurotransmitters" is a good proposal, but don't know any specific information yet. i haven't seen, or heard of, any studies on which neurotransmitters, and in which blending of them, are sequentially produced by specific steps in the jhana (Theravadin Buddhist) system.
i believe it is more likely that, as you say "each approach (even non Theravadin Buddhist) develops the neurotransmitter system...to "feel better" and therefore support further practice." Neurotransmitters are all about feeling good, and those behaviors, whatever they are, are reinforced.
your model doesn't speak to the mystical experience level, which can correspond to levels apparently as high as those produced by the serotonergic psychedelics, which is simultaneously maintained.
Some good proposals and reasoning here; will be great to see the Sharp paper, as you say.