In my post Vipassana meditation and Buddhist psychology, I commented that Buddhism does not explain how meditation neurologically generates peace of mind and that understanding this may help us increase access and use of the practice. Driven by that curiosity, I read a post by Michael Edward Johnson titled The Neuroscience of Meditation: Four Models (dated December 2018). As most research about states of mind, the post uses complex terms. So, after reading a few times and investigating the linked material, I wrote up this simplified summary. Before the content, I need to caveat that these ideas are proposals and the scientific community has not reached a consensus regarding them.
The introduction of the article overlaps with my post Vipassana meditation and Buddhist psychology: Buddhism is a paradigm to eliminate psychological pain (i.e. suffering). Buddhism proposes that identification with wanting generates the self. Meditation helps realise experientially that sensations are impermanent and impersonal and reduce compulsion to reflexively cling to objects of craving or aversion. Then, the author uses three neuroscientific theories to make hypotheses of what Vipassana meditation may do to the brain.
The first is predictive coding, a theory saying that the brain constantly generates and updates models of reality. In doing so, the brain aims to minimise surprise, or the errors in the predictions of its models (also called free energy). Perceptions result as a combination of bottom-up raw sensations and top-down predictions. The self is the model that provides a context for all the other mental models. The author suggests that evolution primed us to create models of ourselves wanting things, so that we strive to survive, which generates suffering. Within the theory of predictive coding, meditation is a way of observing physical sensations without identifying with them. In turn, this prevents sensations from being incorporated in our mental models of ourselves, making the models smaller and less stressful, leading to less suffering.
The second neuroscientific theory mentioned is connectome-specific harmonic waves. Neurons in the brain activate in vibrating patterns (i.e. brainwaves). The theory represents brain states as correlated brainwaves with specific consonant configurations, namely harmonics. Brains can change their configuration and produce certain harmonics more or less easily. Again, the author suggests that to motivate survival, evolution primed us to amplify dissonant harmonics which correspond to unpleasant brain states, or suffering. It seems that these dissonant harmonics are generated by smaller local harmonics coupling together and that meditation may reduce dissonances by dampening this coupling mechanism.
Thirdly, the author discusses neural annealing, a metaphor from metallurgy of how healing may happen neurologically. As the brain changes configurations, it is likely that it builds up internal stress in its connections. These stressful connections can be released in high-energy brain states that are more neutral and plastic. Empirical evidence suggests that meditation and psychedelics produce high-energy states and iterating their practice over time can produce a brain that is structurally optimised against stress. The author suggests that in the case of meditation it is because bottom-up sensations are high-energy whereas top-down predictions are inhibitory. Focusing attention on sensations and letting thoughts come and go may help reach high-energy brain states.
To conclude, the author discusses how we may combine the three models. He suggests that emotions may be bundles of low frequency harmonics that act as input data for the predictive models. Also, as prediction errors build up, the brain naturally enters high-energy states making it more likely to reconfigure information and find a new balance with lower levels of error.
The theories together also suggest that meditation may involve two phases. On one hand one needs to remove psychological barriers that prevent the brain from reaching a minimal level of harmonic resonance. This may occur as trying to meditate, experiencing struggles and working to resolve them. On the other hand, when meditating leads to a spontaneous flow, this may correspond to the neural annealing process that slowly shapes the brain into a more resonant configuration. This seems to mirror to the experiences of meditators.
May you all have resonant brains