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.