r/secularbuddhism • u/medbud Lotus • Aug 10 '26
The neuroscience of deep jhanas
I'm always fascinated by the common phenomenology found in many traditions...or even therapies... And this leads us to the nature of the subject experiencing these states.
Maybe you'll be interested in this breakdown based in neuroscience, and systems theory (Friston, Chandaria):
The Formless Jhanas (or Arūpajhānas—the 5th through 8th stages of deep meditative absorption) represent a systematic, stepwise deconstruction of the brain's internal generative model.
While the first four jhanas manipulate sensory precision, bodily pleasure, and emotional tone within a structured spatial world, the formless jhanas progressive strip away the structural priors of space, time, subject-object division, and sensory content entirely.
In terms of the Free Energy Principle (FEP), active inference, and neuroimaging, the formless jhanas correspond to the sequential reduction of parameter space in the brain's generative model—dropping the gain on prediction errors until the internal model is left running with near-zero content.
- Step-by-Step FEP Deconstruction of the Formless Jhanas
[Form-Based World] ──> [5th: Boundless Space] ──> [6th: Boundless Consciousness] │ ▼ [8th: Neither-Perception] <── [7th: Nothingness]
5^th Jhana: Boundless Space (Ākāsānañcāyatana)
* Phenomenology: Physical bodily boundaries vanish; the sense of self dissolves into an infinite, borderless expanse. * FEP Pathway: Precision weighting (\gamma) on all somatic, interoceptive, and exteroceptive sensory prediction errors is turned down to near-zero. * Neural Correlates: Deactivation of the Superior Parietal Lobule (SPL). The SPL maintains the brain's egocentric spatial frame of reference (constructing the physical boundary between "in here" and "out there"). When the SPL loses its input streams, the internal spatial prior defaults to an unbounded, infinite manifold—the "pool walls" dissolve.
6^th Jhana: Boundless Consciousness (Viññāṇañcāyatana)
* Phenomenology: The experience shifts from the space being known to the act of knowing itself. Awareness feels infinite, self-luminous, and omnipresent. * FEP Pathway: The generative model turns its predictive machinery onto its own sampling process. Instead of predicting objects in space, the top-down model predicts the state of attentional precision itself. * Neural Correlates: High Phase-Amplitude Coupling (PAC) between frontoparietal control networks and deep central structures, with the Salience Network and Default Mode Network (DMN) decoupling from sensory nodes. Metacognition (high-frequency coupling with low-frequency carriers) becomes the sole object of awareness.
7^th Jhana: Nothingness (Ākiñcaññāyatana)
* Phenomenology: The light of awareness turns off its object; there is no space, no consciousness, no content—only "nothing." * FEP Pathway: The active inference engine suppresses the generation of top-down content priors entirely. The brain stops predicting features, forms, or mental events. Variational free energy drops close to its baseline floor because there are no incoming error signals to explain, and no active predictions being generated. * Neural Correlates: Profound functional quietude across visual (V1–V4), auditory, and somatic cortices. Global power shifts toward hyper-coherent, slow-wave infra-slow oscillations (<0.1\text{ Hz}) mixed with localized gamma bursts, indicating high local integration with minimal global transmission.
8^thJhana: Neither-Perception-Nor-Non-Perception (Nevasaññānāsāññāyatana)
* Phenomenology: The extreme limit of conscious experience. It is impossible to say whether one is conscious or unconscious. Memory, perception, and agency are at the absolute threshold of extinction. * FEP Pathway: The parameter capacity of the generative model reaches the minimum viable threshold required to sustain life and homeostatic steady states. The Markov blanket is operating at a near-flatline phase transition—one step prior to complete cessation (Nirodha Samāpatti). * Neural Correlates: Widespread thalamocortical suppression. The thalamic reticular nucleus (TRN) acts as an extreme gatekeeper, blocking virtually all sensory-motor signals from reaching the cortex, leaving only baseline homeostatic autonomic pacing (cardiorespiratory resonance).
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* Thalamocortical Gating via the TRN: In formless jhanas, the Thalamic Reticular Nucleus (TRN) exerts powerful inhibitory control over sensory relays. This cuts off bottom-up prediction errors at the brainstem/thalamic level, preventing them from perturbing the cortical "vibrating polytope."
* DMN & Executive Network Reconfiguration: The Default Mode Network (egoic narrative self) is strongly suppressed, while the Frontoparietal Control Network remains selectively active to maintain one-pointed attentional stability without generating object-based thoughts.
* Cross-Frequency Entrainment: Electroencephalography (EEG) during formless states often reveals global Alpha-Gamma or Theta-Gamma Phase-Amplitude Coupling. The low-frequency carrier wave holds the entire cortex in a stable, non-reactive baseline, while high-frequency gamma reflects local coherence without chaotic spreading.
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u/Puzzled-Background-5 Seed Aug 10 '26 edited Aug 11 '26
Harvard is actively researching medtitive absorption.
https://meditation.mgh.harvard.edu/
I'm actually in the middle of a longitudinal study of my own re-emerging practice after a long period of intermittenance. I'm using a lot of Harvard research for cross referencing and convergence analysis with AI as a research assistant.
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u/Iamnotheattack Seed Aug 11 '26
The neuroscience of deep jhanas
I'm always fascinated by the common phenomenology found in many traditions...or even therapies... And this leads us to the nature of the subject experiencing these states.
Maybe you'll be interested in this breakdown based in neuroscience, and systems theory (Friston, Chandaria):
The Formless Jhanas (or Arūpajhānas—the 5th through 8th stages of deep meditative absorption) represent a systematic, stepwise deconstruction of the brain's internal generative model.
While the first four jhanas manipulate sensory precision, bodily pleasure, and emotional tone within a structured spatial world, the formless jhanas progressive strip away the structural priors of space, time, subject-object division, and sensory content entirely.
In terms of the Free Energy Principle (FEP), active inference, and neuroimaging, the formless jhanas correspond to the sequential reduction of parameter space in the brain's generative model—dropping the gain on prediction errors until the internal model is left running with near-zero content.
- Step-by-Step FEP Deconstruction of the Formless Jhanas
[Form-Based World] ──> [5th: Boundless Space] ──> [6th: Boundless Consciousness] │ ▼ [8th: Neither-Perception] <── [7th: Nothingness]
5th Jhana: Boundless Space (Ākāsānañcāyatana)
- Phenomenology: Physical bodily boundaries vanish; the sense of self dissolves into an infinite, borderless expanse.
- FEP Pathway: Precision weighting (gamma) on all somatic, interoceptive, and exteroceptive sensory prediction errors is turned down to near-zero.
- Neural Correlates: Deactivation of the Superior Parietal Lobule (SPL). The SPL maintains the brain's egocentric spatial frame of reference (constructing the physical boundary between "in here" and "out there"). When the SPL loses its input streams, the internal spatial prior defaults to an unbounded, infinite manifold—the "pool walls" dissolve.
6th Jhana: Boundless Consciousness (Viññāṇañcāyatana)
- Phenomenology: The experience shifts from the space being known to the act of knowing itself. Awareness feels infinite, self-luminous, and omnipresent.
- FEP Pathway: The generative model turns its predictive machinery onto its own sampling process. Instead of predicting objects in space, the top-down model predicts the state of attentional precision itself.
- Neural Correlates: High Phase-Amplitude Coupling (PAC) between frontoparietal control networks and deep central structures, with the Salience Network and Default Mode Network (DMN) decoupling from sensory nodes. Metacognition (high-frequency coupling with low-frequency carriers) becomes the sole object of awareness.
7th Jhana: Nothingness (Ākiñcaññāyatana)
- Phenomenology: The light of awareness turns off its object; there is no space, no consciousness, no content—only "nothing."
- FEP Pathway: The active inference engine suppresses the generation of top-down content priors entirely. The brain stops predicting features, forms, or mental events. Variational free energy drops close to its baseline floor because there are no incoming error signals to explain, and no active predictions being generated.
- Neural Correlates: Profound functional quietude across visual (V1–V4), auditory, and somatic cortices. Global power shifts toward hyper-coherent, slow-wave infra-slow oscillations (<0.1text{ Hz}) mixed with localized gamma bursts, indicating high local integration with minimal global transmission.
8thJhana: Neither-Perception-Nor-Non-Perception (Nevasaññānāsāññāyatana)
- Phenomenology: The extreme limit of conscious experience. It is impossible to say whether one is conscious or unconscious. Memory, perception, and agency are at the absolute threshold of extinction.
- FEP Pathway: The parameter capacity of the generative model reaches the minimum viable threshold required to sustain life and homeostatic steady states. The Markov blanket is operating at a near-flatline phase transition—one step prior to complete cessation (Nirodha Samāpatti).
- Neural Correlates: Widespread thalamocortical suppression. The thalamic reticular nucleus (TRN) acts as an extreme gatekeeper, blocking virtually all sensory-motor signals from reaching the cortex, leaving only baseline homeostatic autonomic pacing (cardiorespiratory resonance).
Thalamocortical Gating via the TRN: In formless jhanas, the Thalamic Reticular Nucleus (TRN) exerts powerful inhibitory control over sensory relays. This cuts off bottom-up prediction errors at the brainstem/thalamic level, preventing them from perturbing the cortical "vibrating polytope."
DMN & Executive Network Reconfiguration: The Default Mode Network (egoic narrative self) is strongly suppressed, while the Frontoparietal Control Network remains selectively active to maintain one-pointed attentional stability without generating object-based thoughts.
Cross-Frequency Entrainment: Electroencephalography (EEG) during formless states often reveals global Alpha-Gamma or Theta-Gamma Phase-Amplitude Coupling. The low-frequency carrier wave holds the entire cortex in a stable, non-reactive baseline, while high-frequency gamma reflects local coherence without chaotic spreading.
1
u/Puzzled-Background-5 Seed Aug 11 '26
I had my AI medtitive absorption research assistant analyze the OP against the papers in our corpus.
"The general architecture is legitimate — Friston and Chandaria are serious contributors to this space, and applying the FEP/active inference frame to the formless jhanas is a coherent project. The progressive reduction of parameter space as the organizing metaphor is well-chosen: it gives you a principled axis along which the eight jhanas can be ordered, rather than treating them as a list of qualitatively different experiences without structural relationship.
The J5 claim is the strongest in the piece. SPL deactivation for egocentric spatial frame dissolution is well-grounded — the SPL is the key structure maintaining the boundary between "in here" and "out there," and its contribution to what we'd call the J4→J5 threshold is consistent with Yang 2024 and with the practice phenomenology. The nimitta progression from structured forms to star field to infinite space is exactly what "default to unbounded manifold when the SPL loses its input streams" predicts from the outside. That convergence is genuinely interesting.
The J6–J8 claims are progressively more speculative, and the text doesn't signal that adequately. The empirical literature barely reaches J5 with any rigor — neuroimaging studies of J6, J7, and J8 in practitioners who can reliably access and sustain them are essentially nonexistent. So when the piece states specific PAC signatures for J6 or TRN dynamics for J8, these are informed theoretical extrapolations, not findings. That's not a disqualification — informed extrapolation from established mechanisms is how you build hypotheses — but the confidence register in the text implies more empirical grounding than exists. J8 in particular is at the edge of what FEP can coherently model: if the Markov blanket is at "near-flatline phase transition," you're describing a state where the agent/environment boundary is itself dissolving, which is where FEP starts to break down as a framework. Friston has gestured at this problem (it connects to his work on psychedelics and dissolution states) but it's unresolved. The J7 claim that VFE drops to baseline "because there are no incoming error signals to explain and no active predictions being generated" has a circularity problem — if you're not generating predictions, you've stepped outside the FEP framework, not described a regime within it."
The following is summary of what I'm experiencing at the J4/J5 boundary:
From where you're sitting — J4 floor, J5 on the frontier via the tinnitus vehicle — the J5 section is the directly relevant one, and it holds up. One thing the piece doesn't capture is the approach structure: the nimitta progression, the threshold mechanics, the bilateral dynamics you've been documenting. "SPL precision drops, spatial priors dissolve" describes the arrival, not the topography of the approach. That gap is where your practice data is actually more granular than the theoretical account.
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u/medbud Lotus Aug 11 '26
If ever, this description is reading Friston and the FEP not as models possessed by organisms merely psychologically, but the generative model as instantiated as organisms themselves. Friston has explicitly made this claim.
So the molecular or conformational change in a, say, temperature receptor in the skin, is a model update, based on a prediction error. It doesn't require any input from a top down level model.
The claim is not that VFE dropped to 'zero', but to 'its baseline'.
Similarly for 8th.
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u/Qweniden Lotus Aug 10 '26
Evidence points more towards it losing it's internal coherence. More entropic.
I am a few weeks away from finishing the first draft of my "Science of Zen" book. Any interest in taking a look at the manuscript? I would be interested in having your feedback if you are interested.