# [Contemplative Science and the Nature of Reality](releases/2025/Contemplative%20Science/Contemplative%20Science.md) # Chapter 8: Beyond Baseline *Neural Dynamics of Deep States and Subtle Signals* While the previous chapter mapped the foundational neuroscientific findings concerning common meditation practices and their impact on core brain networks, the ultimate aim of many contemplative paths extends far beyond basic mindfulness or focused attention. Practitioners seek to cultivate profound states of deep meditative absorption (*Jhana*, *Samadhi*), experiences of radical self-transcendence or unity consciousness, and potentially even states of complete cessation (*Nirodha*). Investigating the neural underpinnings of these advanced states presents formidable challenges to current neuroscientific methods but holds immense potential for illuminating the upper reaches of human consciousness and the brain’s capacity for profound transformation. This chapter ventures into this more challenging territory, reviewing the limited but growing body of research attempting to capture the **neural signatures of deep absorption states** and experiences of **ego dissolution or mystical union**. We discuss the inherent methodological hurdles and examine the tentative findings emerging from EEG and fMRI studies of highly experienced practitioners. Furthermore, we broaden our neuroscientific lens beyond conventional measures of neural activity (fMRI BOLD, standard EEG analysis) to consider the potential relevance of less-studied or more subtle neural phenomena. We explore the possible roles of **local field potentials (LFPs)**, **glial cell activity** (specifically astrocyte calcium signaling), and **ephaptic coupling** (non-synaptic field effects) in shaping complex brain states and subjective experience, acknowledging the speculative nature of these inquiries. Finally, we touch upon the crucial challenge of understanding the neural basis not just of the content of consciousness, but of its **subjective qualities**, such as the sense of certainty or vividness often associated with contemplative insights. ## 8.1 Neural Signatures of Deep Absorption Investigating the neural correlates of deep meditative absorption states, such as the Buddhist Jhanas or Yogic Samadhi, pushes the boundaries of current neuroscientific methodology. These states are traditionally described as involving profound internal stillness, significant withdrawal from external sensory input, intense and stable positive affect (ranging from rapture and bliss to profound equanimity), exceptional mental unification, and sometimes radical alterations in the sense of self, body schema, and time perception. Reliably inducing and sustaining such states within the noisy, physically restrictive, and often anxiety-provoking environment of an fMRI scanner, or while wearing a cumbersome EEG/MEG apparatus, presents obvious difficulties. Characterizing these states accurately also relies heavily on nuanced subjective reports from highly trained practitioners, which can be challenging to elicit precisely and correlate temporally with rapidly changing neural signals. Consequently, dedicated neuroscientific studies focusing specifically on these deep absorption states remain relatively scarce compared to the large body of research on basic mindfulness or focused attention. Despite these significant challenges, some tentative findings and plausible hypotheses are emerging, primarily from **EEG studies** involving highly experienced practitioners capable of reporting entry into Jhana-like states. These studies sometimes reveal distinctive electrophysiological patterns not typically seen during ordinary waking consciousness or basic meditation. Potential findings include widespread and sustained increases in **alpha frequency power** (8-13 Hz), often interpreted in this context not just as relaxation but potentially reflecting active inhibition of sensory processing or internal gating. Sustained increases in lower frequency **theta power** (4-8 Hz), often linked to deep internal focus, memory processes, and altered states like hypnosis or drowsiness, have also been reported. Perhaps more controversially, some studies report bursts of high-amplitude, synchronized **gamma oscillations** (>30 Hz), which have been speculatively linked to states of heightened awareness, feature binding, cognitive integration, or even feelings of bliss, although the precise functional significance of gamma activity remains debated and highly context-dependent. Some reports also suggest a global reduction in the overall variance or complexity of the EEG signal during deep absorption, possibly reflecting the profound mental unification and stillness described phenomenologically. However, it must be emphasized that these EEG findings are not always consistent across studies, individuals, or specific Jhana levels, highlighting the need for more research employing rigorous methodologies, including careful phenomenological validation and longitudinal designs. **fMRI studies** attempting to capture the neural correlates of deep absorption are even rarer and face greater challenges due to the technique’s poor temporal resolution and sensitivity to movement. Hypotheses based on the phenomenology suggest potential neural signatures that future research might target. Given the reported withdrawal from external input, one might predict **profound reductions in activity within primary sensory cortices** (visual, auditory, somatosensory) during deep Jhana states. Altered activity within **thalamocortical loops**, which play a critical role in gating sensory information flow to the cortex and regulating levels of arousal and awareness, might also be expected. Considering the deep mental quietude and absence of discursive thought reported, one could hypothesize **extreme suppression or functional decoupling of the Default Mode Network (DMN)**, potentially exceeding the levels of deactivation observed during basic meditation. Investigating the neural correlates of the intense positive affect (bliss in lower Jhanas, equanimity in higher Jhanas) associated with these states might involve examining activity patterns in reward-related circuits (like the nucleus accumbens, ventral tegmental area), interoceptive regions (like the anterior insula), and emotion regulation networks (prefrontal cortex), potentially revealing unique signatures distinct from ordinary pleasure or calmness. Obtaining clear fMRI evidence for these specific states, however, remains a significant frontier, requiring innovative experimental paradigms (perhaps involving experienced practitioners signaling state transitions) and careful interpretation. ## 8.2 Correlates of Self-Transcendence, Unity, and Ego Dissolution Perhaps even more challenging for neuroscience, yet potentially more revealing about the fundamental nature of consciousness and selfhood, is the investigation of peak contemplative or mystical experiences involving **self-transcendence, unity consciousness, and ego dissolution**. These experiences, described across traditions as moments of profound insight or union (as discussed in Chapter 2), involve a fundamental breakdown or dissolution of the ordinary sense of being a separate, bounded self, often replaced by a feeling of merging with the environment, the cosmos, all beings, or an ultimate reality. Understanding how the brain, the apparent seat of the self, mediates such radical shifts in self-perception is a key goal for a mature contemplative neuroscience and consciousness research more broadly. From a neurological perspective, these states are hypothesized to involve significant alterations in the activity and connectivity of the large-scale brain networks responsible for constructing and maintaining the multifaceted sense of self. This includes not only the **Default Mode Network (DMN)**, heavily implicated in narrative self-reference and mind-wandering, but also crucial regions in the **parietal cortex**. Areas like the **inferior parietal lobule (IPL)**, **superior parietal lobule (SPL)**, and **precuneus** are known to be critical for spatial awareness, distinguishing self from other, integrating multisensory information to form the body schema (sense of body ownership and location), establishing a first-person egocentric perspective, and potentially representing agency. Therefore, **decreased activity or altered functional connectivity** in these parietal regions is frequently hypothesized to underlie the blurring of self/other boundaries, the sense of spatial boundlessness or merging with the environment, and the altered sense of agency reported in unity experiences or states of ego dissolution. Neurological studies of patients with damage to these parietal areas sometimes report related phenomena like out-of-body experiences, altered body ownership (asomatognosia), or difficulties in self-other distinction, lending some plausibility to this hypothesis regarding functional modulation in healthy individuals during altered states. The potential role of specific **neurochemical systems** in modulating self-experience and facilitating self-transcendent states is also an active area of investigation, partly informed by parallel research on the effects of classic **psychedelic substances** (like psilocybin, LSD, DMT) which can induce temporary states of ego dissolution, unitive consciousness, and mystical-type experiences that share some phenomenological overlap with spontaneously occurring or meditation-induced states. These substances primarily act as agonists or partial agonists at **serotonin 2A (5-HT2A) receptors**, which are densely expressed in high-level cortical regions, including the DMN and parietal cortex. Neuroimaging studies during psychedelic administration often show decreased DMN integrity, altered global functional connectivity (sometimes described as increased brain entropy or complexity), and changes in parietal activity, which correlate with subjective reports of ego dissolution. While the mechanisms inducing these states are clearly different (exogenous drug vs. endogenous practice), this research raises the possibility that endogenous modulation of the serotonin system, perhaps achievable through specific advanced contemplative practices or occurring spontaneously in certain states, could play a role in gating access to experiences of self-transcendence. However, directly testing this hypothesis in meditators is extremely difficult, and the precise relationship between drug-induced states and advanced contemplative attainments remains an area of active debate and requires careful comparative research. Capturing the often spontaneous, transient, and deeply subjective nature of these peak experiences neuroscientifically remains a major methodological challenge, frequently relying on retrospective reports correlated with resting-state brain activity or requiring specialized experimental designs capable of capturing rare events. ## 8.3 Investigating Non-Spike Signals: LFPs and Information Content The vast majority of non-invasive human neuroscience research, including studies of meditation, relies on measures that primarily reflect the consequences of neuronal **action potentials (spikes)**–either indirectly through hemodynamic coupling (fMRI BOLD) or through the synchronized extracellular fields generated by population spiking and synaptic activity (EEG/MEG). However, an increasing body of evidence suggests that focusing solely on spikes might provide an incomplete, and potentially misleading, picture of neural information processing and its relation to complex cognitive states and subjective experience. There is growing interest in the potential role of other types of neural signals, particularly **local field potentials (LFPs)**, in understanding brain function and consciousness. LFPs primarily reflect the aggregate **synaptic activity** (summed excitatory and inhibitory postsynaptic potentials) and dendritic processing within a local population of neurons, rather than their output spiking. They represent the slower, graded fluctuations in the extracellular electrical field within a specific brain region. Research, primarily from invasive recordings in animals (and occasionally humans undergoing neurosurgery for clinical reasons), indicates that LFPs carry rich and distinct information about sensory stimuli, motor intentions, attentional states, and cognitive processes–information that is sometimes more predictive of behavior or subjective state than spike rates alone. LFPs are also closely related to the macroscopic oscillations observed in scalp EEG and MEG signals and are thought to play a crucial role in coordinating activity and facilitating communication between different brain regions through oscillatory synchronization. The potential relevance of LFPs to contemplative neuroscience is intriguing, though currently largely speculative due to the significant methodological challenges of measuring LFPs directly and non-invasively in humans (although MEG potentially offers the best non-invasive window onto LFP-related activity). Could the subtle shifts in the quality of awareness, the felt sense of presence, the binding of conscious content into a unified whole, or the profound stability and stillness of global brain states achieved in deep meditation be better reflected in the complex dynamics of LFPs rather than just in spike patterns or overall BOLD signals? Could the inherently field-like nature of LFPs, reflecting the integrated activity of local populations, relate more directly to the holistic, unified, or field-like subjective experiences (e.g., boundless awareness, unity consciousness) sometimes reported by advanced practitioners? Answering these questions requires further development of non-invasive recording techniques or, more likely, innovative analytical approaches applied to existing high-temporal-resolution data (like MEG or high-density EEG) that might allow for better inference of LFP dynamics and their information content. Exploring the role of LFPs represents a significant frontier in understanding the neural code and its relationship to subjective experience, potentially offering new insights into the unique characteristics of contemplative states that go beyond standard spike-based analyses. ## 8.4 Glial Contributions: Astrocyte Calcium Signaling in Cognition? Neuroscience has traditionally operated under a strongly **neuron-centric** view, considering neurons as the primary, if not exclusive, information processing units of the brain. **Glial cells**, which include astrocytes, oligodendrocytes, and microglia, were historically relegated to primarily supportive roles: providing structural support, metabolic resources, insulation (myelin), and immune functions. However, this view is rapidly evolving, particularly concerning **astrocytes**, the most abundant glial cell type in the mammalian brain, which significantly outnumber neurons in some regions. There is now compelling evidence that astrocytes play active roles in brain function, moving far beyond mere support. Astrocytes form intricate networks throughout the brain, intimately associate with neuronal synapses (forming the “tripartite synapse”), regulate local blood flow (neurovascular coupling, the basis of the fMRI signal), control the extracellular environment (ion concentrations, neurotransmitter uptake), and, crucially, communicate with each other and with neurons through complex signaling mechanisms. A key mechanism involves fluctuations in intracellular **calcium (Ca2+) concentration** within astrocytes. These calcium signals can propagate as waves through astrocyte networks and trigger the release of various signaling molecules (“gliotransmitters”) that can, in turn, modulate neuronal excitability and synaptic transmission. This astrocyte calcium signaling operates on much **slower timescales** (typically seconds to minutes) compared to the millisecond timescale of neuronal action potentials. Evidence, primarily from sophisticated experiments in animal models (often using techniques like two-photon calcium imaging), indicates that these slow glial signals can actively modulate synaptic plasticity (learning and memory), influence neuronal firing patterns and network oscillations, coordinate activity across larger neuronal populations, and contribute to complex processes like sleep regulation and sensory processing. This raises the speculative but fascinating question of whether glial activity, particularly astrocyte calcium signaling, might contribute directly to subjective experience or play a significant role in shaping contemplative states. Could the slow, stable, and enduring nature of deep meditative states be related, in part, to the slower integrative dynamics of glial networks operating in concert with neuronal networks? Could astrocyte signaling contribute to the overall subjective tone or quality of consciousness, or perhaps play a role in the long-term neural plasticity and trait changes associated with sustained contemplative training? Establishing such links in humans is currently extremely difficult, as non-invasively measuring astrocyte activity with high fidelity remains a major technological challenge. While the idea that glia actively contribute to cognition and potentially consciousness is gaining significant traction within neuroscience, its specific relevance to contemplative science remains a highly speculative but potentially important frontier, encouraging a move beyond a purely neuron-centric understanding of the meditating brain. ## 8.5 Ephaptic Coupling: Field Effects in Neural Processing? Another non-conventional mechanism of neural communication that has garnered intermittent interest and occasional speculation regarding its role in consciousness is **ephaptic coupling**. This refers to interactions between neurons that are mediated by the **extracellular electric fields** generated by their own activity, rather than occurring through direct synaptic connections. When neurons fire action potentials or undergo synaptic activity, ions flow across their membranes, creating electrical currents that propagate through the surrounding extracellular space. These currents generate local electrical fields (which are essentially what LFPs measure). Ephaptic coupling occurs when these extracellular fields generated by one neuron or group of neurons directly influence the voltage across the membrane of nearby neurons, thereby altering their excitability and firing probability, independent of synaptic transmission. The functional significance of ephaptic coupling in the complex environment of the mammalian brain is still debated and likely depends heavily on factors like neuronal geometry, packing density, and the strength and synchrony of neural activity. Compared to the strong and specific effects of synaptic transmission, ephaptic effects are generally considered to be weaker and less spatially precise. However, theoretical models and some experimental evidence (primarily from simpler neural systems or specific brain structures like the hippocampus or olfactory bulb) suggest that ephaptic coupling could play a role under certain conditions, particularly in **synchronizing the firing of closely packed neuronal populations**, modulating the timing of action potentials, and potentially influencing network oscillations, especially fast rhythms like gamma oscillations (>30 Hz) which involve highly synchronized activity. The potential relevance of ephaptic coupling to contemplative states is highly **speculative** but intriguing to consider. Could ephaptic interactions contribute to the generation or maintenance of the large-scale, high-frequency synchrony (e.g., gamma coherence across distant brain regions) that has sometimes been reported in the EEG of highly experienced meditators during states of deep concentration or compassion? Could the inherently field-like nature of this interaction bear any relation to the holistic, unified, or field-like subjective experiences (e.g., boundless awareness, experiences of energy fields) reported by some practitioners? Establishing such connections faces enormous challenges. Experimentally isolating ephaptic effects from the overwhelmingly dominant synaptic effects in the intact human brain is currently almost impossible. While ephaptic coupling represents a known physical mechanism for non-synaptic neural interaction, its actual contribution to complex cognitive functions or subjective states like those achieved in meditation remains largely theoretical and lacks strong empirical support. Nonetheless, considering such field effects encourages exploration of the full repertoire of potential neural communication mechanisms beyond the standard synaptic model. ## 8.6 Neural Basis of Subjective Qualities A final frontier for contemplative neuroscience, and indeed for consciousness science as a whole, involves moving beyond simply correlating neural activity with the presence or absence of specific cognitive *content* (e.g., perceiving an object, thinking a thought, feeling a basic emotion) towards understanding the neural basis of the **subjective qualities** or **phenomenal tone** that accompany experience. Subjective reports from contemplative practice often place great emphasis on these qualitative aspects: the profound sense of **certainty** or conviction that can accompany a deep insight; the exceptional **vividness** or clarity of perception or mental imagery in certain states; the deep feeling of **presence** or **reality** associated with an experience; or the specific **affective tone** (such as bliss, peace, unconditional love, or profound equanimity) that pervades a particular meditative state. These qualities are often considered just as important, if not more so, than the specific content of the experience. Understanding how the brain generates these subjective qualities presents a significant challenge, closely related to the hard problem of consciousness itself. What neural mechanisms underlie the feeling of certainty or the “aha!” moment associated with transformative insights gained during meditation? Research in cognitive neuroscience on decision-making suggests that confidence signals might be computed in specific prefrontal cortical regions (like orbitofrontal cortex or rostrolateral PFC), potentially based on the strength or stability of sensory evidence or internal models, but how this relates to the profound, life-altering certainty reported in contemplative breakthroughs remains largely unexplored. What determines the subjective vividness of mental imagery or the felt sense of presence and reality? Perhaps the level and stability of activation in relevant sensory cortices, the degree of synchronization between different brain regions, the precision weighting assigned within predictive processing frameworks, or the influence of specific neuromodulatory systems plays a role. The characteristic affective tones of advanced meditative states–the deep peace (*shanti*) of Samadhi, the energetic bliss (*pīti*, *sukha*) reported in the lower Jhanas, the warmth of boundless compassion (*mettā*, *karuṇā*), the unshakable balance of equanimity (*upekkhā*)–likely involve specific and stable patterns of activity within the brain’s emotion-related circuits (including amygdala, insula, ACC, nucleus accumbens, periaqueductal gray) and potentially the sustained release or altered balance of key neurochemicals (e.g., endogenous opioids, dopamine, serotonin, oxytocin, GABA). Could specific oscillatory signatures (e.g., sustained alpha or theta rhythms) or particular patterns of large-scale network connectivity also contribute to these pervasive subjective qualities, creating a global brain state conducive to these affects? Investigating the neural basis of these often subtle but phenomenologically crucial aspects of contemplative experience requires innovative experimental designs that carefully link nuanced, fine-grained first-person reports (using methods discussed in Chapter 17) with sophisticated neural measures (potentially including neurochemical or multi-modal approaches). Pushing towards understanding the neural basis of subjective quality, not just content, is essential for a truly comprehensive neuroscience of contemplation and consciousness. --- [9 Brain as Processor](releases/2025/Contemplative%20Science/9%20Brain%20as%20Processor.md)