The Brain in Indian Medical and Religious Traditions: A Relational Organ Model of Mastiṣka, Hṛdaya, and Nāḍī

Abstract

This article examines the concept of the brain (mastiṣka) within the Indian intellectual tradition, tracing its development from the magico-religious medicine of the Atharvaveda (c. 1200–900 BCE) through the classical Āyurvedic texts—the Suśrutasaṃhitā, the Caraksaṃhitā, the Aṣṭāṅgahṛdayasaṃhitā, and the relatively neglected Bhelasaṃhitā—to the subtle-body physiology of Haṭha Yoga literature. Against the background of a comparative analysis with the brain–heart debate in ancient Greek medicine, the article argues that Indian medicine developed a distinctive ‘relational organ model’ in which brain and heart constitute complementary poles of a single vital-cognitive network mediated by the nāḍī (neural-energetic channel) system. This model is neither simply cardiocentric nor encephalocentrist but integrates both within a hierarchical framework. The Bhelasaṃhitā’s unique near-encephalocentrist statement (śiras tālvantare cetanādhiṣṭhānam) reveals a genuine internal debate within classical Indian medicine, while the Haṭhayogic synthesis—locating the ultimate seat of consciousness in the cranial Sahasrāra while preserving the heart as the integrative hub of all channels—represents a coherent integration of both tendencies. The Sāṃkhya philosophical framework provides the metaphysical key to this integration, distinguishing non-material consciousness (puruṣa) from the material cognitive apparatus (antaḥkaraṇa). The article brings into dialogue these historical findings with recent research in neurocardiology, neuroimaging, and prāṇāyāma science to illuminate areas of empirical convergence, contributing to the interdisciplinary dialogue among science, religion, and health on the nature of human flourishing.

1. Introduction

“Where is consciousness located?” This question has animated Indian intellectual history from its earliest Vedic strata to the present day. The dominant tradition in contemporary neuroscience locates consciousness primarily in the brain. Yet this consensus is itself subject to productive revision, as recent research on enteric neural networks, spinal processing, and the intrinsic cardiac nervous system increasingly points toward a distributed, embodied model of cognition that extends well beyond the cerebral cortex (Gershon 1998; Armour 1991; Craig 2002). This distributed turn in contemporary neuroscience renders the Indian relational model—which never assigned consciousness exclusively to a single organ—newly pertinent rather than merely historically interesting. Yet the classical Indian tradition, as attested in the foundational texts of Vedic and Upaniṣadic thought, directed this inquiry toward the hṛdaya—the heart—as the seat of consciousness, life, and the self. How did this “cardiocentrism” eventually accommodate, and in certain texts yield to, a recognition of the brain’s cognitive primacy? And what mediating role did the concept of the nervous-energetic channels (nāḍī) play in this transformation? These are the central questions this article sets out to answer.

The history of consciousness localization is not unique to India. Ancient civilizations confronted the same puzzle and resolved it in strikingly different ways. In Egypt, the brain was discarded during mummification as an inert substance, while the heart was preserved as the seat of intellect and moral character. In Mesopotamia and China—where the heart houses shén (spirit-consciousness)—cardiocentric models similarly prevailed. Only in ancient Greece did an explicit, sustained debate emerge between competing cardiocentric (Aristotelian) and encephalocentrist (Alcmaeon, Hippocratic, Galenic) schools—a debate that decisively shaped Western neuroscience. India’s trajectory was distinct from all of these: neither a simple cardiocentrism nor a resolved encephalocentrism, but a productive tension sustained across millennia, ultimately transformed by the Haṭhayogic synthesis into an integrated heart–brain–energy model of remarkable philosophical sophistication.

Scholarship on this topic may be divided into two major streams: foundational studies in the history of Indian medicine, and recent work on the physiological dimensions of yoga.1 The history of Indian medicine has been illuminated by foundational works (Filliozat 1964; Wujastyk 2003; Meulenbeld 1999–2002; Zysk 2021), while yoga physiology has attracted increasing interdisciplinary attention (Birch 2018; Mallinson and Singleton 2017). The present article engages critically with two active debates within this scholarship. First, there is ongoing disagreement about the extent to which haṭhayogic ‘subtle body’ physiology represents a continuous development from classical Āyurvedic anatomy or constitutes a largely independent soteriological construction: Birch (2018) emphasizes terminological continuity, while Alter (2004) and Jain (2015) caution against underestimating the degree to which modern yoga discourse has retrospectively constructed its classical lineage. This article sides with Birch on the philological evidence of shared technical vocabulary, while acknowledging with Alter and Jain that the Haṭhayogic framework reorganizes its Āyurvedic inheritance within a soteriological register that cannot be reduced to clinical medicine. Second, recent contemplative science has been criticized for applying neuroscientific methods to yoga and meditation without adequately attending to the doctrinal and practical specificity of the traditions under study (Van Dam et al. 2018). The article addresses this concern by consistently distinguishing between the classical textual tradition and its contemporary scientific reception, and by treating neuroscientific findings as empirical data that can enter into dialogue with—but cannot adjudicate—the normative and metaphysical dimensions of the Indian framework. Despite this substantial body of research, no single study has examined the three-way interaction of mastiṣka, hṛdaya, and nāḍī as a coherent historical development across the full span of Indian intellectual history.

By ‘relational organ model’, this article means the distinctive Indian conceptual framework in which brain and heart function not as competing alternatives for the seat of consciousness but as hierarchically integrated poles within a distributed vital-cognitive network, held together and mediated by the nāḍī channel system. This model, rather than resolving the brain–heart debate through experiment or philosophical decree, preserved it as a productive structural tension whose full implications were systematically elaborated across more than two millennia. This article fills that gap by analyzing primary texts in close detail, situating them within the broader cross-cultural debate on consciousness localization, and bringing into dialogue with recent neuroscientific findings. The argument proceeds in three movements: (i) the coexistence, from the earliest Indian literary sources, of cardiocentric metaphysics with empirical observation of the brain as a vital organ; (ii) the internal diversity of classical Āyurvedic positions, culminating in the Bhelasaṃhitā’s unique near-encephalocentrism; and (iii) the Haṭha Yoga synthesis that integrates both tendencies within a hierarchical heart–brain–energy model whose implications for contemporary integrative medicine and philosophy of mind remain largely unexplored.

Methodologically, this article proceeds through three complementary analytical levels that the reader is invited to distinguish throughout. The first is historical and philological analysis: the close reading of primary Sanskrit, Pali, and Chinese sources in their original literary and intellectual contexts, with attention to terminological precision, intertextual dependencies, and the specific historical circumstances of each text’s composition and transmission. This level of analysis makes claims about what specific texts assert and how those assertions relate to one another—claims that are, in principle, verifiable through philological scholarship. The second level is heuristic comparison: the juxtaposition of classical Indian concepts with ancient Greek medicine and contemporary neuroscience for the purpose of mutual illumination. Heuristic comparisons are generative rather than demonstrative: they suggest new questions and reveal structural parallels without asserting historical influence, conceptual identity, or empirical equivalence. The third level is empirical triangulation: the identification of areas where contemporary neuroscientific and clinical research produces findings that are consistent with—though not derived from, and not constituting verification of—classical Indian claims.2 To triangulate, in this technical sense, is not to demonstrate that ancient Indian practitioners ‘anticipated’ modern science, nor to suggest that contemporary neuroscience confirms the soteriological claims of the traditions. It is, rather, to identify a shared empirical domain—the brain–heart–autonomic nervous system nexus—in which both ancient and contemporary investigators have generated systematic observations, and to ask what each body of knowledge can contribute to the other’s understanding. Triangulation thus operates at the level of productive dialogue, not proof: it illuminates the traditions’ empirical achievements without subordinating their religious and soteriological dimensions to a scientific tribunal, and without reducing the traditions’ authentic claims about the nature of consciousness, liberation, and the divine to mere proto-scientific hypotheses.

The present article is situated within the interdisciplinary framework of science, religion, and health, and contributes to this dialogue in three ways. First, the Indian relational organ model (mastiṣka–hṛdaya–nāḍī) represents a case study in how a religious and contemplative tradition—embedded in Vedic ritual, Upaniṣadic metaphysics, Buddhist contemplative practice, and yogic soteriology—generated sophisticated empirical observations about the body, mind, and their interaction that remain productively comparable with contemporary neuroscience. Second, the Sāṃkhya philosophical framework demonstrates how a systematic Indian metaphysics of consciousness can serve as a conceptual bridge between the ‘hard problem’ of subjective experience and the empirical neuroscience of cognition—a bridge that neither reduces religion to science nor places them in irresolvable conflict. Third, the concept of human flourishing (śreyas, yoga, mokṣa) that pervades all layers of this tradition—from Āyurvedic health (ārogya) to Haṭhayogic liberation—offers a normative framework for integrative medicine and contemplative science that is historically grounded, intellectually rigorous, and practically relevant to contemporary debates about what it means to flourish as a human being.

2. Terminological Foundations for the Brain

2.1. The Sanskrit and Pāli Terms: Mastiṣka and Mastuluṅga

Classical Sanskrit possesses two principal lexical items for the anatomical brain. The first and more frequent is mastiṣka (also spelled mastiṣkā). Derived from the root mastaka (“head, skull, crown”) via the diminutive suffix -iṣka, the term thus carries the meaning “what belongs to, or is contained within, the skull.” Its earliest attestation is in the Atharvaveda (10.2.6), where mastiṣka appears alongside hṛd (heart) and śiras (head) as a triad of vitally important anatomical loci. The Pāṇinian grammar (Aṣṭādhyāyī 5.3.86) confirms mastiṣka as a standard technical term. In the Āyurvedic saṃhitās, it consistently designates the cerebral matter within the cranium, described by Suśruta as white, smooth, and soft—closely resembling bone marrow in color and texture—and enclosed by the cranial vault.3

The second Sanskrit term is mastuluṅga, a compound of mastu (cream, the fatty or clarified part of a substance; cognate with mastaka) and luṅga (a soft, marrow-like internal substance). The compound thus evokes the brain’s macroscopic appearance as a pale, fatty, and somewhat gelatinous material—“the soft matter within the skull.” Because this term emphasizes the tactile and morphological qualities of the cerebral tissue that a surgeon would encounter—its consistency, color, and resemblance to marrow—it is particularly favored in surgical contexts. It appears prominently in the Suśrutasaṃhitā (Śārīrasthāna 5.29; Meulenbeld 1999–2002, vol. I, p. 87)—a text with a strong surgical orientation—as the standard term for the cerebral parenchyma.

The Pāli reflex of mastuluṅga is matthaluṅga, which follows regular Pāli phonological rules: Sanskrit mastu → Pāli mattha (with consonant cluster simplification and vowel shortening). The compound matthake matthaluṅgam—“brain [matthaluṅgam] in the skull [matthake]”—appears as the thirty-second item in the Khuddakapāṭha enumeration of bodily constituents, a term explicitly locating the brain within the skull—a topographic specificity absent from the standard thirty-one-item list of the Mahāsatipaṭṭhāna Sutta (Dīgha Nikāya 22, compiled c. 3rd century BCE). This phrase thus encodes both anatomical and spatial knowledge: the brain is not merely named but located.

2.2. Related Terms: Śiras, Mūrdhan, Kapāla, and Śarīrika Marrow

Several related terms intersect with mastiṣka in the classical literature. Śiras (head, including the skull and its contents) is the broadest anatomical designation and functions as the container for mastiṣka. The Bhelasaṃhitā’s encephalocentrist declaration—“consciousness is established in the upper part of the head” (śiras tālvantare cetanādhiṣṭhānam)—uses śiras rather than mastiṣka, indicating that this philosophical claim about the brain’s primacy is expressed through the topographic rather than the anatomical term.

Further related terms include mūrdhan (the crown or vertex of the skull, the topmost point of the head), kapāla (the skull or cranial vault, as a bone structure), and aṭṭhimañjā (bone marrow), which is specifically listed as a tissue distinct from mastiṣka in the canonical enumeration—despite their similar texture—in the Pāli Dhamma tradition (aṭṭhimañjaṃ, “bone-marrow”). This terminological precision demonstrates that Buddhist anatomists were not confusing the brain with bone marrow; they recognized both as distinct constituents of the body, even while employing similar descriptive vocabulary (“soft,” “fatty,” “white”) for each. The reference (Monier-Williams 1899, p. 792) records the full semantic range of mastiṣka as “the brain,” “the pith of a plant,” and “marrow”—confirming that the word operates across a semantic field of “central, vital, soft substance” while retaining its primary anatomical reference to the cerebral contents of the skull.

2.3. Conceptual Implications

The lexical choices made across the textual traditions are themselves conceptually revealing. The predominance of morphological descriptors—terms emphasizing the brain’s texture, color, and location rather than its functions—reflects the primarily anatomical, rather than physiological or cognitive, frame within which the brain was initially understood. The contrast with the term hṛdaya is instructive. Whereas hṛdaya carries a densely layered semantic load—encompassing the anatomical organ, the emotional center, and the seat of consciousness (which we will discuss in detail in the subsequent sections)—mastiṣka remains primarily a physical and locative term. This terminological asymmetry precisely tracks the philosophical asymmetry that this article traces: the heart is the organ of consciousness; the brain is its container. The terminological evidence thus corroborates—and partially explains—why the cognitive elevation of the brain required not just new anatomical observations but a restructuring of the entire conceptual vocabulary through which organs were understood to participate in the life of the mind. Greek medicine resolved this by simply choosing enkephalos (“what is in the head”) over kardia as the seat of the soul; Indian medicine resolved it by reconceiving the relationship between the two organs, rather than subordinating one to the other. The terminological and conceptual parallel between Sanskrit mastiṣka and Greek enkephalos—both locative compounds meaning “what is inside the head”—is striking and may reflect the shared Indo-European heritage of anatomical naming, though any direct historical connection would require further philological investigation (Crivellato and Ribatti 2007, p. 833).4

3. From Magico-Religious to Empirical Medicine

3.1. Mastiṣka in the Atharvaveda: The First Physical Brain Concept

The Atharvaveda (c. 1200–900 BCE) is simultaneously the oldest Indian medical compendium and its most vivid document of magico-religious healing practice.5 The term ‘magico-religious,’ employed here in its established technical sense in the history of medicine (following Zysk 2021 and Filliozat 1964), designates a healing system in which ritual efficacy, cosmological power, and pharmacological knowledge are inseparably integrated. This is not a dismissive characterization of the tradition’s epistemic or religious status. The Atharvavedic healer operated within a complete theological world-view in which disease represented a disruption of cosmic and social order, and healing enacted a restoration of right relationship with divine powers. The mantras and protective rituals of this corpus are not merely indicators of physiological knowledge; they are primary enactments of a soteriology in which bodily health participates in the pursuit of ṛta (cosmic truth, right order) and dīrghāyu (long, flourishing life) as divinely ordained goods. To historicize these practices is not to reduce them to proto-science but to trace how a tradition of divinely ordered healing generated, across centuries, increasingly refined empirical observations about the body—observations that never ceased to be embedded in a religious vision of human flourishing as inseparable from the vision of liberation (śreyas). The text contains hundreds of mantras for the expulsion of disease-causing demons (yakṣa, grāhi, takman), formulas for counteracting witchcraft, and invocations of divine physicians such as the Aśvins. Disease is ontologized as supernatural interference: fever (takman) is addressed as a divine being whose departure is implored rather than caused through natural means.

Yet interwoven with this magico-religious fabric is a remarkably empirical pharmacopoeia. Specific plants—kṣīṇī, apāmārga, śatāvarī—are prescribed for identifiable conditions with detailed botanical descriptions. The Atharvaveda distinguishes between healing with auṣadha (plant medicines) and with mantra (sacred formulas), and many hymns deploy both simultaneously, suggesting a pragmatic integration of empirical and symbolic resources. Filliozat (1964, p. 12) argued that the Vedic healer’s observational knowledge of herbal efficacy was systematically accumulated across generations, forming the empirical substrate from which classical Āyurveda would eventually crystallize.

What Zysk (2021) calls the “shaman-physician” of the Atharvavedic period—a practitioner who healed through both material interventions and ritual performance—prefigures the radical methodological transformation of the classical period, when Buddhist monastic communities and Brahmanical medical lineages alike would insist that diagnosis and treatment be grounded in direct observation (pratyakṣa) and rational inference (anumāna).6

While the Upaniṣads elaborate a metaphysical topology of consciousness centered on the heart, the Atharvaveda provides the earliest unambiguous designation of the brain as a distinct physical organ. In Atharvaveda 10.2.6, a hex formula directed against an enemy invokes the brain, the heart, the head, and the bones as co-equal vital targets, calling for the destruction of all simultaneously: “Let loose the brain (mastiṣka), whatever is in the mouth, the heart (hṛd), the head (śiras), and the bone—destroy all of that of yours.”7

The structural importance of this passage is its collocation of mastiṣka with hṛd (heart) and śiras (head) as parallel vital centers in a single formula. The brain and heart are conceptually co-equal here as seats of life—distinguished from each other but assigned equivalent vital importance. This early co-designation prevents any simple narrative of Indian thought as purely and originally cardiocentric and establishes the brain–heart pair as a foundational dyad in Indian body-knowledge.

Elsewhere in the Atharvaveda (6.47.1; 19.3), hṛd is associated with emotion (joy, grief, love, fear) while manas carries the connotation of thought, will, and intention, and mastiṣka designates the physical substance in which these mental activities are grounded. According to commentators cited by Zysk, mastiṣka is described as a fatty, white, moist substance within the skull—a description that accurately captures the macroscopic appearance of brain tissue.8

3.2. Anatomical Knowledge and the Śava-Vicāra Method

The transition from magico-religious to empirical medicine accelerated with the systematic accumulation of anatomical knowledge. The Suśrutasaṃhitā describes the śava-vicāra method—the controlled examination of a corpse through sequential decomposition—by which Suśruta and his school acquired detailed anatomical knowledge.9 Through this systematic procedure, Suśruta enumerated 300 bones, described 107 vital points (marma), catalogued 700 vessels (sirā), and mapped the body’s seven structural tissues (saptadhātu).10

Wujastyk (2003, p. 65) characterizes this empirical programme as representing “the examination of dead human bodies for the study of anatomy” The crucial implication for our purposes is methodological: the śava-vicāra establishes that Āyurvedic anatomical knowledge was, at least in part, grounded in direct observation of the human body. The brain’s characterization as white, fatty, and marrow-like in Āyurvedic texts is consistent with—and likely derived from—exactly such observational practice.

3.3. Early Buddhist Anatomical Traditions: Matthaluṅga in Pāli Sources

The term matthaluṅga (Pāli; Skt. mastuluṅga)—denoting the brain as the soft, marrow-like substance within the skull—appears in several early Buddhist canonical texts, demonstrating that anatomical knowledge of the brain was integrated into the Buddhist intellectual tradition well before the Āyurvedic classical period. The Mahāsatipaṭṭhāna Sutta (Dīgha Nikāya 22) enumerates thirty-one bodily constituents as objects of mindful contemplation—a practice designed to loosen the meditator’s attachment to the body. While the standard list does not include the brain, a closely related text, the Khuddakapāṭha (3: Dvattiṃsākāraṃ), extends the enumeration to thirty-two items by adding matthake matthaluṅgam—“the brain in the skull”—as its final entry.11

This addition is significant for two reasons. First, it confirms that the anatomical vocabulary for the brain (matthaluṅga) was well established in early Buddhist canonical usage. Second, the brain’s position as the last—and seemingly supplementary—item in the body-part enumeration reflects an ambivalent status: acknowledged as a somatic constituent but not integrated into the dominant physiological or metaphysical framework. This marginalization runs parallel to the Āyurvedic characterization of mastiṣka as derived from kapha doṣa rather than as an independent locus of consciousness, and to the Upaniṣadic tradition’s consistent redirection of inquiry toward the hṛdaya. The Buddhist canonical tradition thus provides independent corroboration of a broader cross-traditional pattern: empirical familiarity with the brain coexisting with its theoretical subordination.

3.4. Jīvaka’s Craniotomy: The Brain as a Surgical Object

According to the Sanskrit-Tibetan recension of the Mūlasarvāstivāda Vinaya, Jīvaka Komārabhacca acquired his craniotomy technique through direct apprenticeship with the physician Ātreya at Takṣaśilā (Taxila), then the preeminent centre of medical education in the Indian subcontinent.12 The transmission process is characteristically pedagogical: when Jīvaka observed Ātreya attempting to extract a parasitic worm from a patient’s opened skull using forceps, he proposed an improvement—heating the instrument so that the worm would retract its legs and be more easily withdrawn. Ātreya, recognizing Jīvaka’s exceptional clinical insight, thereupon transmitted the complete technique of cranial surgery to him (Zysk 2021, pp. 71–72; Salguero 2017, pp. 190–91; cf. Schopen 2004).

The Vinaya sources preserve three distinct surgical cases attributed to Jīvaka. (i) The most fully documented case, reported in both the Pāli Vinaya Piṭaka (Cīvarakhandhaka) and the Chinese Sifenlü 四分律 (T22, 852b–c), concerns a wealthy merchant of Rājagaha who had suffered from debilitating headaches for seven years. Jīvaka administered alcohol to induce analgesia, secured the patient to a bed, incised the scalp, opened the skull at the suture, and successfully extracted two worms—one large, one small—from the cranial cavity.13 After removing the worms, Jīvaka packed the empty cranial space with ghee (酸, sū) and honey (蜜) before closing the wound, after which the patient recovered without scarring and with full regrowth of hair. (ii) A second case, recorded in the Sanskrit-Tibetan Vinaya, describes Jīvaka diagnosing a centipede lodged within the brain of a patient presenting with an itching scalp lesion, employing a diagnostic gemstone for visualization before opening the skull and removing the parasite with a heated instrument. (iii) A third account, preserved in the Chinese Foshuo nưqí yù yīnyuán jīng 佛説榮女祉域因緣經 (T553), narrates Jīvaka reviving a fifteen-year-old girl who had died on her wedding day from a cerebral worm infestation: he opened the skull with a golden knife, extracted all worms, and applied three specialized ointments—one to repair the bone, one to regenerate brain tissue, and one to close the incision—after which she revived within seven days (Zysk 2021, p. 79).

Whether or not these accounts are historically accurate, their intellectual significance is independent of their factual status. Taken together, they constitute a coherent surgical tradition in which the brain is treated as an accessible anatomical site, open to diagnosis and physical intervention. The accounts agree on several technical features: the use of pharmacological agents (alcohol, ghee, honey) for analgesia and post-surgical repair, the strategic opening of the cranial sutures, the removal of pathological agents from within the brain parenchyma, and the deployment of biological substances for wound closure. By the fifth century BCE, Indian educated culture could not only conceive of the brain as a site of pathology but could articulate a systematic surgical approach to it—a development that stands in instructive tension with the philosophical tradition’s sustained cardiocentrism.

3.5. The Brain in Buddhist Meditative Visualization: Zhì Chán Bìng Mì Yào Fǎ

A strikingly different engagement with brain anatomy appears in the fifth-century Chinese Buddhist therapeutic text Zhì Chán Bìng Mì Yào Fǎ 治禪病秘要法 (T620), translated in southern China c. 454 CE. This manual addresses somatic and psychological pathologies arising during intensive meditation practice—the so-called chán bìng 禪病 (“meditation sickness”)—and prescribes detailed visualization sequences as their cure. The most elaborate of these, the “Enveloping Butter Contemplation,” makes direct use of neuroanatomical imagery: the meditator visualizes 404 channels (mài 脈) extending from the scalp into the brain, the brain itself as composed of four regions and 98 layers, and a symbolic craniotomy in which a divine figure removes a portion of the skull and pours medicated clarified butter into the cranial cavity, the liquid flowing through the brain’s channels downward through the entire body to the tips of the toes.14

This visualization draws on the same anatomical vocabulary—brain, channels, cerebrospinal substance—that appears in Āyurvedic accounts of Tarpaka kapha and mastiṣka, but deploys it within a soteriological rather than a clinical framework. It should be noted, however, that the precise transmission pathway between Indian Āyurvedic brain anatomy and this Chinese Buddhist text remains uncertain: the text’s peculiar neuroanatomical details (four brain regions, 98 layers) do not correspond to any known Indian or Chinese medical system, suggesting that this may represent an independent Chinese scholastic elaboration for soteriological purposes rather than direct transmission from Āyurvedic sources. The cranial space is symbolically re-sealed, and the body surrounded by a protective barrier against pathogenic winds (vāta). This convergence suggests that, by the fourth or fifth century CE, detailed brain anatomy had become sufficiently widespread in Buddhist communities across South Asia and into Chinese Buddhism to serve as a ready-made matrix for meditative imagination—that is, for the deployment of anatomical imagery as a vehicle of soteriological transformation, where the body becomes the site of liberation rather than merely a clinical object. To describe this as ‘meditative imagination’ is not to suggest that the practice is less real or less efficacious than clinical intervention; it is to distinguish the soteriological register—in which the body is engaged as a means toward liberation—from the clinical register—in which the body is treated as an object of therapeutic intervention. Both registers take the body seriously; they differ in their ultimate horizon. This distinction is itself internal to the Indian traditions, which consistently differentiate between ārogya (health as clinical goal) and mokṣa (liberation as soteriological goal), while insisting that the former is a necessary, if insufficient, foundation for the latter. A transmission pathway that runs parallel to, and occasionally intersects with, the Āyurvedic clinical tradition traced in subsequent sections.

4. The Heart (Hṛdaya) as Seat of Consciousness: Upaniṣadic Metaphysics

4.1. Hṛdaya: The Metaphysical Heart and Its Physiological Network

The Upaniṣadic understanding of hṛdaya represents the single most influential framework for consciousness localization in Indian intellectual history. Across the principal Upaniṣads—Chāndogya, Bṛhadāraṇyaka, Kaṭha, Muṇḍaka, and Maitrī—the heart is consistently described as the dwelling (āyatana) of the ātman, the seat of the absolute self, and the source from which all vital channels radiate throughout the body.15

The Chāndogya Upaniṣad (8.1.1–3) provides the most elaborated account. The text describes the heart as a small lotus-shaped dwelling (daharam puṇḍarīkaṃ veśma) within the city of brahman (brahma-pura, i.e., the body), containing an interior space (dahara ākāśa) in which brahman dwells, infinite in extension despite being located within the finite body: “Now, within this city of brahman, there is a small lotus-shaped dwelling. Within it is a small space. One should search for what is within it, for that is what one should want to discover.”16

In the Bṛhadāraṇyaka Upaniṣad, the cardiac topology receives a striking physiological elaboration. The text specifies that the heart contains 101 principal nāḍīs, each branching into 100 subsidiary channels, each branching further into 72,000 minor channels, through all of which prāṇa flows. One specific channel runs upward from the heart through the crown of the head as the vehicle of immortality: “Of the heart’s channels, there are one hundred and one. One of them runs up through the crown of the head; going upward through it, one reaches immortality.”17

This physiological detail is crucial for our argument. Brain and heart are already in structural communication in the earliest Upaniṣadic physiology: the network of 72,000 channels18 originates from the heart but extends to the crown of the head, establishing a continuous pathway from cardiac center to cranial apex that the Haṭha Yoga tradition would later develop into the Suṣumṇā axis of kuṇḍalinī ascent. The transition from the Upaniṣadic heart-center to the Haṭhayogic brain-center is not a rupture but an elaboration of structural possibilities already present in the foundational texts.

4.2. Manas as the Mediating Faculty

A crucial intermediary in the Upaniṣadic model is manas (mind), understood not as identical with either heart or brain but as a discrete cognitive faculty mediating between them. In the Kaṭha Upaniṣad’s hierarchical model, the sense objects are higher than the senses, manas is higher than the sense objects, buddhi (intellect) is higher than manas, and the great self (mahān ātmā) is higher than buddhi: “Higher than the senses are their objects; higher than the objects is the mind (manas); higher than the mind is the intellect (buddhi); higher than the intellect is the great self.”19

The material brain is not explicitly named in this hierarchy, but the evidence of the Atharvaveda suggests it was understood as the physical substrate of manas’s operations. The Upaniṣadic model thus implies a three-term structure: ātman (pure consciousness, dwelling in the heart) → manas (mind, functioning at or through the brain) → indriyas (sense organs, distributed throughout the body). The Āyurvedic synthesis would make this implicit tripartition explicit.

4.3. The Sāṃkhya Philosophical Framework: Consciousness, Cognition, and the Body

The Upaniṣadic tripartition of ātman, manas, and indriya receives its most rigorous systematic articulation in the Sāṃkhya school of Indian philosophy, which provides the explicit philosophical backbone for classical Āyurveda’s otherwise puzzling dual claim: that consciousness resides in the heart while all cognitive faculties reside in the brain. Understanding this claim requires grasping Sāṃkhya’s foundational distinction between puruṣa (pure, non-material consciousness) and prakṛti (primordial material nature, encompassing all that is subject to evolution, transformation, and causal process). As codified in Īśvarakṛṣṇa’s Sāṃkhyakārikā (c. 350–450 CE), puruṣa is unqualified, inactive, and non-local—it is not in the brain, not in the heart, not anywhere in physical space. Prakṛti, by contrast, evolves a hierarchical series of material principles, among which the cognitive apparatus (antaḥkaraṇa, “inner instrument”) is the most refined.20

The antaḥkaraṇa consists of three faculties: buddhi (intellect, the principle of determination and discrimination; the first and finest evolutionary product of prakṛti), ahaṃkāra (ego-sense, the individuating principle that appropriates experience as “mine”), and manas (mind, the coordinator of incoming sensory data and outgoing motor impulses). In Sāṃkhya metaphysics, all three are unambiguously material—subtle, to be sure, composed of sattva-dominant refined matter, but material nonetheless. The cognitive functions that Suśruta locates in the brain (buddhi, manas, ahaṃkāra, and all the sense organs; Suśruta Saṃhitā, Sūtrasthāna 14.3) are, within this framework, precisely the fine-material instruments of the inner apparatus located in their most refined physical substrate.21

This Sāṃkhya distinction between material cognition and immaterial consciousness dissolves the apparent contradiction between Suśruta’s encephalocentric cognitive physiology and Caraka’s cardiocentric consciousness theory. For Caraka, who adopts Sāṃkhya’s puruṣa-prakṛti framework most explicitly, the heart is not the source of consciousness but its somatic ādhāra—the organ through which non-material puruṣa most intimately contacts the body, providing the subjective warmth of felt experience. The brain, as the seat of buddhi and ahaṃkāra, is the locus of cognitive processing—the material mirror in which puruṣa’s light is reflected and articulated into thought, discrimination, and self-sense. Consciousness and cognition are thus placed at different ontological levels, with different organs as their respective somatic anchors. It is this Sāṃkhya two-level ontology, not any inconsistency of observation or doctrine, that generates what appears to modern readers as the tension between Āyurveda’s cardiocentric and encephalocentric moments.22

The three guṇas (sattva, rajas, tamas) that pervade all prakṛti further provide Sāṃkhya’s most nuanced psychophysiological model for understanding the brain’s functional states. In their cognitive applications, sattva manifests as clarity, discrimination, and reflective awareness—the qualities of an optimally functioning buddhi; rajas manifests as activity, passion, and motivational drive—the character of manas in its sensory–motor engagement with the world; and tamas manifests as inertia, opacity, and structural stability—the quality underlying bodily mass and vegetative processes. The Āyurvedic tridoṣa model of the brain’s functional pathology maps with remarkable structural precision onto this Guṇa framework: excess vāta’s qualities of lightness and mobility correspond to rajas-dominance; excess kapha’s heaviness and stability correspond to tamas-dominance; and excess pitta’s heat and transformation to an inflamed rajas that overwhelms sattva’s clarity. Both systems describe not what the brain is in structural isolation, but what the brain does within a broader field of energetic relationships—a description operating at the level of dynamic process rather than static anatomy, and entirely consistent with the relational organ model this article has been tracing.23 An important qualification must be registered here, however. Classical Sāṃkhya is a non-theistic system: it posits no divine creator and treats liberation as the result of discriminative knowledge (viveka) between puruṣa and prakṛti rather than of divine grace. Classical Yoga, by contrast, incorporates an additional principle—Īśvarapraṇidhāna (devotion to the Lord)—as both a soteriological path and a metaphysical postulate (Sāṃkhyakārikā of Īśvarakrṣṇa distinguishes from the theistic Yoga of Patañjali). Āyurvedic medicine draws on Sāṃkhya-Yoga philosophy as a practical theoretical framework without resolving this theological difference; it operates across both theistic (Vaiśṇava, Śiva) and non-theistic Brahmanical contexts. Devotional medicine, as attested in texts such as the Carakaṃhitā’s ethical framework and in the religious obligations of the physician (ācārya), acknowledges that healing ultimately participates in a moral and spiritual cosmos—whether that cosmos is understood theistically or not. For a practitioner oriented toward liberation (mokṣa), bodily health is not an end in itself but a necessary foundation; for an ordinary householder (gṛhastha), ārogya is sought as a condition for the fulfillment of social and ritual obligations (dharma, artha, kāma). The Indian concept of human flourishing thus operates on a graduated scale: different goods are appropriate to different stages of life (the āśrama system) and different orientations of the person. This article traces the common structural features of the relational brain–heart–nāḍī model across these diverse orientations while acknowledging that the ultimate significance of bodily cultivation—whether as health management, moral formation, or spiritual liberation—varies significantly depending on the practitioner’s vocation and theological commitments. The implications of this Sāṃkhya two-level ontology—distinguishing non-material puruṣa from the material antaḥkaraṇa—for the contemporary neuroscience–consciousness dialogue are taken up directly in Section 7, where the structural parallel with Chalmers’s (1995) ‘hard problem’ and with neurocardiology’s discovery of the cardiac neural system are examined as cases of empirical triangulation rather than doctrinal confirmation.

5. The Medical Functions of the Brain in Classical Āyurveda

5.1. The Suśruta Saṃhitā: The Brain as the Seat of Buddhi and the Senses

Of the three foundational Āyurvedic texts, the Suśruta Saṃhitā engages most directly with the physical brain. Suśruta’s tradition was primarily surgical (śalya-tantra), and his anatomical observations are correspondingly more detailed and physiologically explicit than those of the internist Caraka. The brain is classified as mastuluṅga: the marrow-substance filling the cranium, understood as the most refined specialization of majjā dhātu (bone-marrow tissue) in the body’s seven-tissue hierarchy.24

In the Śārīrasthāna (chapter on the body), Suśruta describes the brain as enclosed within two bony plates, smooth and unctuous, white and marrow-like in texture: “The palate (tālu) [is the floor] of the skull (śiras); within it rests the brain (mastiṣka)—unctuous, smooth, and white like marrow—enclosed by two bony plates.”25 This is an accurate macroscopic description based on direct observation.

The functional declaration in the Sūtrasthāna goes further, placing intellect (buddhi), mind (manas), wisdom (dhī), ego-sense (ahaṃkāra), and all the sense organs (indriyāṇi sarvāṇi) within the brain (mastiṣka): “Intellect, mind, wisdom, ego-sense, and all the sense organs—all are located in the brain.”26

Suśruta continues to note that brain injury produces immediate loss of these functions—sensory paralysis, motor impairment, aphasia—and ultimately death. The causal chain between cranial trauma and neurological deficit is explicitly articulated, attributing higher mental functions to the physical organ of the brain. The four śṛṅgāṭaka marma (cranial vital points), which are classified as immediately fatal on severe injury (Wujastyk 2003, p. 240), represent Suśruta’s clinical operationalization of this knowledge into surgical risk assessment.27

Furthermore, Meulenbeld (1999–2002, vol. IB, p. 87) highlights that both the Suśrutasaṃhitā and the Aṣṭāṅgahṛdayasaṃhitā describe certain bodily structures (snāyu) as originating directly from the brain tissue (mastuluṅga), which may mean the nerves. This crucial anatomical insight suggests early Āyurvedic attempts to understand the brain not just as a static mass, but as a physiological origin point for neural or sinewy connections

5.2. The Caraksaṃhitā: Cardiocentrism with Functional Brain Recognition

The Caraksaṃhitā occupies a philosophically different position. Caraka’s tradition was internal medicine (kāya-cikitsā), governed by a Sāṃkhya-Yoga philosophical framework in which consciousness (cetanā) is fundamentally non-material—an emanation of puruṣa that manifests in the body through the medium of the heart.28 Caraka declares: “The heart is the seat of consciousness.”29

For Caraka, the brain is acknowledged as a mahā-marma (major vital point) and as the location of tarpaka kapha—the kapha subdoṣa that nourishes the sense organs—but it is not designated as the seat of consciousness or the primary cognitive organ. Consciousness operates through the heart; the brain serves the sense organs. This relational complexity is present even within the Carakasaṃhitā itself. As Meulenbeld (1999–2002, vol. IB, p. 59) acutely observes, there is a locational tension in Caraka’s description of the seats of life (prāṇāyatana): while one passage designates the head as the seat of prāṇa (Carakasaṃhitā 17.12), another explicitly assigns this role to the heart (Carakasaṃhitā 30.11). This internal textual tension strongly supports the concept of a bipolar model of vital function rather than an exclusive cardiocentrism.

Critically, however, Caraka’s own textual tradition contains evidence that complicates this simple cardiocentrism. The Aṣṭāṅgahṛdayasaṃhitā locates Prāṇa Vāyu, the most vital of the five air-functions governing all higher cognition, in both the brain (mūrdhan) and the heart (hṛdaya): “Prāṇa resides in the brain and in the heart.”30 This dual locus—the only instance in the doṣa taxonomy where a subdoṣa explicitly spans both brain and heart—is the strongest classical Āyurvedic textual evidence for an integrative brain–heart model of vital function.31

5.3. The Aṣṭāṅgahṛdayasaṃhitā: Tridoṣa Theory and the Brain as Kapha’s Refined Essence

Vāgbhaṭa’s Aṣṭāṅgahṛdayasaṃhitā (c. 7th century CE) synthesizes the Caraka and Suśruta traditions within a comprehensive Tridoṣa framework. It specifies: “The brain is the refined essence (sāra) of kapha.”32 In Āyurvedic doṣa theory, kapha governs structure, lubrication, cohesion, and stability. The brain, as kapha’s purest concentrated form, is accordingly the most structurally stable and cognitively refined organ—the apex of the body’s constructive principle.

The pathological corollaries are systematically developed. When kapha is disturbed in the brain, cognitive functions are impaired: excess kapha produces mental heaviness, torpor, and cognitive dulling; excess vāta in the brain produces anxiety, tremor, insomnia, and dissociation; excess Pitta produces inflammatory encephalitic states and emotional volatility. This is a doṣa-based neuropsychology of considerable sophistication.

The closely related concept of tarpaka kapha—the cranial subdoṣa that nourishes all sense organs—has been proposed as an Āyurvedic analogue for cerebrospinal fluid (CSF): both are continuously produced, fill cranial and spinal spaces, nourish neural tissue, and are colorless and slightly viscous.33 Suśruta’s observation that aggressive nasal medication can cause brain-marrow leakage may possibly document some degree of clinical awareness of a CSF-rhinorrhoea-like phenomenon; however, this interpretation should be treated with caution, as the Āyurvedic description does not explicitly identify a distinct fluid compartment analogous to the modern CSF concept, and the comparison remains, at this stage, a hypothesis requiring further philological and clinical evaluation.

5.4. The Bhelasaṃhitā: An Alternative Tradition and Near-Encephalocentrism

The Bhelasaṃhitā, approximately contemporaneous with the Caraksaṃhitā and representing an independent school of classical Āyurveda, occupies a unique and underappreciated position in this history. Its Śārīrasthāna contains a consciousness-localization statement found nowhere else in Sanskrit medical literature: “The seat of consciousness (cetanādhiṣṭhāna) is between the top of the head (śiras) and the palate (tālu).”34

As Valiathan (2003, p. 44) observes, this is the nearest approach to encephalocentrism in all of classical Indian medicine. The spatial description—between the cranial vault and the palate—unmistakably designates the brain as its referent. Meulenbeld (1999–2002, vol. IIA, p. 23) confirms the passage’s textual authenticity and the Bhela school’s independence from the Caraka tradition, making it impossible to dismiss this statement as a later interpolation or derivative formulation.35

In addition to its unique locational claims, the Bhelasaṃhitā provides distinct quantitative anatomical observations. It explicitly measures the volume of the brain (mastiṣka) as one añjali (the volume of two cupped hands), thus solidifying its status as a discrete, quantifiable physical organ rather than an amorphous substance (Meulenbeld 1999–2002, vol. IIA, p. 19). The Bhelasaṃhitā (Śārīrasthāna 5.10–12) also contains descriptions of a furrowed brain surface and five internal cranial chambers (koṣṭha) filled with “pure kapha” (śuddha-śleṣman), each associated with distinct sensory or cognitive functions. These passages have been cautiously interpreted as early descriptions of the cortical gyri and cerebral ventricles, respectively. Taken together, the Bhela evidence reveals a genuine internal debate within classical Indian medicine. The tradition did not speak with one voice on the question of consciousness localization; the Bhela school constitutes an alternative current that, had it prevailed, might have directed Indian neuroscience toward an explicitly brain-centered model centuries before the colonial encounter with European anatomy.

The fact that the Bhela school’s near-encephalocentrist position did not prevail in the mainstream Āyurvedic tradition requires explanation. Several converging factors are likely responsible. First, the Bhelasaṃhitā is attested in only a single, severely damaged manuscript tradition, suggesting that its transmission was always marginal and geographically circumscribed compared to the widely disseminated Caraka and Suśruta lineages. Second, the dominant intellectual framework of Indian classical thought—the Sāṃkhya-Yoga cosmology adopted by Caraka—provided a principled philosophical reason for cardiocentrism (consciousness as puruṣa, manifesting through manas anchored in the heart) that the Bhela encephalocentrism could not easily displace without a wholesale revision of the cosmological framework. Third, the institutional context of medical education in the Brahmanical and Buddhist lineages privileged the practical clinical traditions of Caraka (internal medicine) and Suśruta (surgery) over the more speculative anatomical philosophy of the Bhela school. The result was not suppression but marginalization: the Bhela tradition survived in fragmentary form while the mainstream preserved its cardiocentric metaphysics and its functional brain knowledge as complementary, rather than competing, frameworks.

6. The Nāḍī System in Haṭha Yoga: A Synthesis of Medical and Metaphysical Traditions

6.1. The Subtle Body (Sūkṣma Śarīra): Conceptual Foundations

The Haṭha Yoga tradition, crystallizing between the 10th and 15th centuries CE, inherits both the Upaniṣadic metaphysics of the cardiac consciousness-space and the Āyurvedic clinical knowledge of the physical brain. Its distinctive contribution is the doctrine of the subtle body (sūkṣma śarīra)—an energetic infrastructure that interpenetrates and animates the gross physical body, structured around the nāḍī-cakra-prāṇa system. The earliest Haṭha yoga text, the Amṛtasiddhi, frames this in alchemical terms; the mature Haṭhayogapradīpikā systematizes it as a comprehensive physiology of liberation.36

The nāḍī system posits 72,000 channels through which prāṇa (vital energy) flows. These nāḍīs are not identical with nerves or blood vessels; they are the energetic infrastructure that makes the nervous and vascular systems physiologically coherent. Their blockage (nāḍī-duṣṭi) produces disease; their purification (nāḍī-śuddhi) through prāṇāyāma and āsana is the foundational practice of Haṭha yoga. As Birch (2018) has demonstrated through systematic philological comparison, the Haṭhayogic nāḍī-cakra framework shares 78 technical terms with Āyurvedic literature, attesting to its deep roots in the medical tradition.37

The transition from the Āyurvedic clinical brain (Section 5) to the Haṭhayogic subtle body (Section 6) is not a sharp discontinuity but a conceptual transformation: the anatomical and physiological knowledge accumulated in the saṃhitā literature—the brain as refined kapha essence, prāṇa vāyu spanning brain and heart, the nāḍīs radiating from the cardiac center—provided the building blocks that Haṭha Yoga reorganized within a soteriological framework oriented toward liberation rather than clinical healing. The key step was the reinterpretation of the physical brain’s cognitive functions as corresponding to the cranial cakras of the subtle body, and the reinterpretation of the Āyurvedic channel system as the nāḍī network through which kuṇḍalinī ascends from the base of the spine to the cranial Sahasrāra.

6.2. Iḍā, Piṅgalā, Suṣumṇā: Mapping the Nervous System in Energetic Terms

Among the 72,000 nāḍīs, three are paramount. The Haṭhayogapradīpikā (3.3–4) describes Iḍā on the left, Piṅgalā on the right, and Suṣumṇā in the middle as the conductor of prāṇa: “Iḍā and Piṅgalā and thirdly Suṣumṇā: Iḍā is on the left side, Piṅgalā on the right, Suṣumṇā in the middle—the conductor of prāṇa.”38 Suṣumṇā runs vertically through the spinal axis (merudaṇḍa), from the mūlādhāra at the base of the spine to the sahasrāra at the crown of the head.

Iḍā (left) and Piṅgalā (right) correspond functionally to the parasympathetic and sympathetic divisions of the autonomic nervous system respectively: Iḍā is described as cooling, lunar, and relaxing (associated with the left nostril), while Piṅgalā is described as heating, solar, and activating (associated with the right nostril). The balance between them—achieved through nāḍī śodhana (alternate nostril breathing)—activates suṣumṇā and enables the meditative states of higher yoga.

The scientific validation of this framework has proceeded along several independent lines. Research on the nasal cycle and cerebral hemispheric lateralization has established synchrony between nostril dominance and contralateral EEG hemispheric dominance, with forced unilateral nostril breathing capable of shifting this lateralization.39 Niazi et al. (2022), using 64-channel EEG with modern source localization in trained yogis, confirmed that dominant nostril breathing significantly increases EEG power in the contralateral inferior frontal and parietal regions.40 These findings are consistent with the yogic claim that Iḍā and Piṅgalā have asymmetric, lateralized effects on brain function, and that their deliberate modulation through prāṇāyāma produces measurable changes in cognitive state.

6.3. The Cakra System: Energetic Topology of Brain–Heart Integration

The cakra system organizes the body’s energetic centers along the Suṣumṇā axis. Three cakras are particularly significant for the brain–heart relationship.

Anāhata cakra (at the cardiac region) is the Haṭhayogic equivalent of the Upaniṣadic hṛdaya: the center of love, compassion, and emotional integration, associated with the physical heart and preserving the Upaniṣadic tradition of the heart as the locus of the personal self and the deepest emotional life.

Ājñā cakra (at the interbrow region, corresponding to the brain) is the center of will, intuition, and higher intellect (buddhi). The Haṭhayogapradīpikā (4.17–21) describes it as the threshold between ordinary sensory consciousness and the transcendent states of samādhi.41 This location is explicitly cerebral, marking the brain’s function as the locus of individual cognitive will and its transformation into superpersonal awareness.

Sahasrāra cakra (at the crown of the head) is described in the Gheraṇḍa Saṃhitā (3.68) as the point where “the yogin attains unity with brahman” upon kuṇḍalinī’s arrival.42 Its location at the cranial summit makes it the Haṭhayogic tradition’s definitive relocation of consciousness’s ultimate seat from the Upaniṣadic heart-space to the brain’s highest point.

The Haṭhayogapradīpikā (4.29) preserves the Upaniṣadic heritage in a formulation that simultaneously asserts the heart’s structural centrality: “All the networks of nāḍīs converge in the heart (sarvāṇi nāḍījālāni hṛdaye saṃkucanti).”43 The heart functions as the energetic integrating center from which all 72,000 channels radiate and to which they return—the hub of the body-wide network. The brain (Sahasrāra) is the apex of the consciousness-transformation process that travels through this network. Brain and heart are not competing alternatives but hierarchically integrated poles within a single system.

7. Comparative Perspectives

The Indian trajectory is most sharply defined by comparison with ancient Greece, where the cardiocentrism–encephalocentrism debate was conducted explicitly and at length. Alcmaeon of Croton (c. 500 BCE) first identified the brain as the seat of sensation and intelligence through anatomical dissection and clinical observation of head trauma. The Hippocratic text On the Sacred Disease (c. 400 BCE) declared that pleasures, joys, laughter, and reason all originate from the brain, characterizing it as “the most powerful organ of the human body.” Plato’s Timaeus located the immortal soul in the spherical head.

Yet Aristotle—whose authority in subsequent millennia exceeded that of any other Greek thinker—argued for the heart as the primary organ of sensation and intelligence, relegating the brain to a merely cooling function. His grounds were embryological (the heart forms first in development) and physiological (warm blood correlates with intelligence; the brain is relatively bloodless and cold). The Aristotelian-cardiocentric position dominated Greek philosophy until Galen (129–216 CE) conducted a decisive experimental neuroscientific programme—systematic nerve-cutting, spinal cord sectioning, and ventricular manipulation—that restored encephalocentrism to unassailable scientific authority.44 This structural complexity in the Indian tradition is also mirrored at the semantic level. Meulenbeld (1999–2002, vol. IB, p. 59) notes that the Sanskrit term hṛd(aya) encompasses a broad semantic field that includes both the physical heart and the cardiac region—an ambiguity that precisely parallels the interpretative challenges encountered in ancient Greek medical texts when localizing cardiac functions.

India’s resolution of this debate differs structurally from Greece’s. Where Greek medicine produced competing schools whose tensions were resolved through experimental neuroscience, Indian medicine maintained a productive ambiguity: the philosophical tradition (Upaniṣads, mainstream Āyurveda) preserved cardiocentrism; the surgical tradition (Suśruta) developed sophisticated brain-focused functional knowledge; the Bhela school articulated a near-explicit encephalocentrism; and Haṭha Yoga synthesized all three within a hierarchical model in which both heart and brain have irreducible and complementary functions.

The prāṇa-pneuma parallel is the most illuminating cross-cultural comparison. Both concepts are etymologically derived from breath; both serve as intermediaries between the physical body and consciousness; both circulate through channel systems and are manipulated through breathing practices. Filliozat (1964, pp. 142–65) identified five structural homologies between the two concepts: (i) the shared etymological root in ‘breath’; (ii) the intermediary role between matter and consciousness; (iii) fivefold subdivision in some Greek schemes; (iv) the centrality of respiratory manipulation for therapeutic and spiritual purposes; and (v) the pathological consequences of disruption to the system’s normal flow. Crucially, Filliozat concluded that these homologies reflect independent parallel development rather than direct transmission—a conclusion reinforced by Wujastyk (2003, xli), who confirmed the complete absence of Greek loanwords in Āyurvedic technical vocabulary, in striking contrast to Sanskrit astronomical texts of the same period, which contain extensive Yavana (Greek) borrowings. This linguistic evidence indicates that the structural convergences between prāṇa and pneuma arose from independent responses to similar problems of physiological explanation rather than from cultural contact. McEvilley (2002) explores these parallels within a broader Indo-Greek comparative framework.45

The temptation to read ancient Indian body concepts as anticipations of modern science—prevalent in popular Āyurveda and yoga discourse—requires methodological caution. Ancient anatomical and physiological frameworks operated within their own epistemic presuppositions and terminological systems. The nāḍī is not a nerve; prāṇa is not electromagnetic energy; the sahasrāra is not the pineal gland.46 The appropriate stance is critical dialogue: treating ancient frameworks as generating genuine observational data and productive conceptual distinctions while applying contemporary scientific methods to evaluate their claims empirically on the frameworks’ own terms.47

The most significant area of convergence concerns neurocardiology. The following paragraphs operate at the third methodological level identified above—namely, empirical triangulation—and the comparisons they draw are explicitly heuristic rather than demonstrative: they identify areas of functional resonance between ancient frameworks and modern findings without asserting conceptual identity, historical influence, or causal equivalence. The discovery of the intrinsic cardiac nervous system—comprising approximately 40,000 neurons organized in ganglionated plexuses within the cardiac wall, capable of independent sensory processing, memory, and local reflex activity—vindicates, in a qualified sense, the Āyurvedic cardiocentric intuition.48 The heart is not merely a pump; it is a sensory organ and a neural processing center. Crucially, 80–90% of vagal nerve fibres run from heart to brain (afferent), so the heart transmits more information to the brain than it receives (McCraty 2022, pp. 305–6). Cardiac neural signals reach the amygdala, thalamus, hypothalamus, and prefrontal cortex, affecting emotion, cognition, and pain perception—findings that resonate directly with Caraka’s characterization of the heart as the seat of both cetanā and ojas.

The scientific evidence for nāḍī śodhana’s autonomic and cognitive effects is now substantial. Ghiya’s systematic review (Ghiya 2017) of 44 randomized controlled trials of alternate nostril breathing (nāḍī śodhana prāṇāyāma) found high-level evidence for positive effects on autonomic nervous system balance, cardiopulmonary function, and cognitive performance. Mittal et al.’s (2025) RCT confirmed significant blood pressure reduction and improved heart rate variability in hypertensive patients after six weeks of daily practice. For the brain specifically, Gothe et al. (2019) found consistent yoga-associated increases in gray matter volume in the hippocampus, frontal cortex, anterior cingulate, and insular cortex across eleven neuroimaging studies.49 Plini et al. (2025) reported significantly enhanced MRI signal intensity in the pineal gland of long-term meditators alongside a meaningfully reduced predicted brain age—the first morphometric evidence of meditation-associated structural brain differences involving a specific glandular structure associated in yoga discourse with the ājñā region.50 It is important to note that this finding does not reinstate the post-Theosophical equation of the ājñā cakra with the pineal gland (discussed in fn. 41 above), which remains a modern construction unsupported by classical texts. What the finding does demonstrate is that long-term meditative practice produces structural effects in a cranial region broadly associated with the ājñā-sahasrāra axis in Haṭhayogic discourse—a convergence at the level of anatomical region rather than specific glandular identity.

These findings do not “prove” the classical Indian framework but demonstrate that practices derived from it produce measurable effects on precisely the organ systems that the tradition identified as central—heart, brain, autonomic nervous system—and in directions consistent with the tradition’s own claims about the effects of those practices. This is not verification but resonance; not concordism but productive dialogue.

The Sāṃkhya-derived conceptual architecture of classical Āyurveda has also attracted sustained attention from cognitive scientists and philosophers of mind. The Sāṃkhya distinction between non-material puruṣa and the material-yet-subtle antaḥkaraṇa foreshadows, in structural terms, the contemporary debate between strong and weak forms of physicalism. David Chalmers’s “hard problem of consciousness”—the explanatory gap between neural processes and subjective experience—maps with striking structural precision onto Sāṃkhya’s two-level ontology: the “easy problems” of cognitive function (attention, memory, executive control) correspond to antaḥkaraṇa operations and are, in principle, tractable by neuroscientific investigation; the hard problem of qualia corresponds to the irreducibility of puruṣa to any material configuration of prakṛti. Sedlmeier and Srinivas (2016, p. 343) have noted this structural correspondence and proposed that Yoga-Sāṃkhya cognition theory generates testable hypotheses about the neural correlates of meditative states precisely because it treats the cognitive apparatus as material while maintaining consciousness itself as a separate, non-reducible datum. Building on this, Tripathi and Bharadwaj’s Yogic Theory of Consciousness (YTC) formalizes the Sāṃkhya vṛtti model—the five modes of mental modification (pramāṇa, viparyaya, vikalpa, nidrā, smṛti)—as a functional taxonomy of neural connectivity patterns, mapping them onto specific fMRI-identifiable default-mode and task-positive network states. Their analysis suggests that the Sāṃkhya-Yoga framework may provide a principled indigenous conceptual grid for organizing neuroscientific data that is at once philosophically coherent and empirically productive.51

8. Conclusions: The Indian Brain—A Relational Model for Human Flourishing

The historical trajectory traced in this article reveals a consistent logic underlying the apparent diversity of Indian positions on brain and consciousness. Whether in the Upaniṣadic heart-centered metaphysics, the Āyurvedic dual-focus of Prāṇa Vāyu in brain and heart, Bhela’s near-encephalocentrism, or the Haṭha Yoga synthesis, the Indian tradition consistently resists the assignment of consciousness to a single anatomical location. Consciousness, in the Indian model, is not produced by a specific organ—it is a relational phenomenon arising through the interaction of multiple centers (heart, brain, sense organs) mediated by the nāḍī network.

This “relational organ” model has features that distinguish it sharply from both ancient Greek encephalocentrism and modern brain-centric neuroscience. First, it maintains that heart and brain are functionally interdependent rather than competing alternatives: disrupting either produces systemic cognitive and vital impairment. Second, it integrates emotional (bhāva), cognitive (jñāna), and vital (prāṇa) functions within a single anatomical network rather than separating them into distinct modules. Third, it maintains the relevance of subjective states—emotional tone, meditative depth, and moral cultivation—for physiological function. This third feature is perhaps the most prescient: psychoneuroimmunology, contemplative neuroscience, and integrative medicine have collectively begun to vindicate the claim that mental and emotional states have systemic physiological consequences, in precisely the ways that Āyurvedic psychosomatics and Haṭhayogic soteriology had long maintained.

The 19th-century colonial encounter precipitated a forced translation of this relational model into European anatomical categories: nāḍī became “nerve,” mastiṣka became “brain” in the narrow anatomical sense, prāṇa was alternately dismissed as pre-scientific mysticism or awkwardly mapped onto “nervous energy.” As Raina (2015) has shown, this translation process both enabled and constrained the integration of Āyurvedic knowledge into the modernizing Indian state’s medical system. The productive path forward is not reverse translation—reading Western neuroscience into ancient Sanskrit—but genuine conceptual dialogue: engaging classical Indian frameworks on their own terms while remaining alert to areas of empirical convergence and methodological complementarity.

The “Indian brain,” as this article has argued, is better understood as a conceptual complex—mastiṣka–hṛdaya–nāḍī—than as a single anatomical organ. It is a brain that is always already in conversation with the heart; always embedded in the distributed network of vital channels; always structured by philosophical commitment to consciousness as fundamentally relational rather than locally produced. In an era when neuroscience itself is increasingly attentive to the brain–body axis, the gut–brain connection, the cardiac–neural system, and the distributed nature of cognitive processing, this ancient Indian relational model offers not merely historical interest but conceptual resources for reconceiving the very questions that contemporary science is beginning to ask anew.

The concept of human flourishing that emerges from this study is irreducibly integrative, yet it is not monolithic. A crucial dimension of the Indian contribution that deserves explicit elaboration concerns the differentiation of flourishing across different types of practitioners and theological commitments—a differentiation that the traditions themselves take with great seriousness and that the present study has only gestured toward in its structural analysis. In the Āyurvedic framework, the concrete goals of medicine differ significantly depending on the patient’s vocation and stage of life. For an ordinary householder (gṛhastha), medicine aims at ārogya—the health necessary to fulfill one’s social, familial, and ritual obligations (dharma, artha, kāma). For a religious practitioner or ascetic (sādhaka), the body becomes the primary instrument of spiritual discipline, and medicine serves the different goal of maintaining the physical conditions under which contemplative practice can be sustained and liberation (mokṣa) pursued. These are not merely different emphases within a single model; they reflect genuinely different understandings of what the body is for and what counts as its proper function. The classical physician (vaidya) was expected to navigate these competing conceptions of the good with both clinical skill and ethical discernment—what Caraka calls the physician’s sattva (moral constitution). Furthermore, the question of human flourishing looks different depending on whether one operates within a theistic or non-theistic framework. Within theistic Vaiśṇava and Śaiva traditions, health is a divinely ordered good, and the body is the vehicle through which devotion (bhakti) is expressed and divine grace (prasanna) received; the heart, as the seat of devotional consciousness, carries a theological weight that exceeds its physiological significance. Within the non-theistic Sāṃkhya framework, by contrast, flourishing is conceived as the progressive clarification of discriminative knowledge (viveka) and the disengagement of puruṣa from the entanglements of prakṛti—a process in which the Āyurvedic cultivation of the body serves as a preparatory discipline for meditative insight. These distinct orientations are not merely academic variations; they generate different practical recommendations and different criteria for what counts as progress toward well-being. The present article’s relational brain–heart–nāḍī model represents a structural common ground across these orientations—a shared anatomical and physiological vocabulary that different theological and soteriological traditions have each deployed in their own way. Recognizing this structural commonality without erasing the differences is, the present authors submit, the appropriate scholarly stance for interdisciplinary work of this kind. Across all layers of the Indian tradition examined here—Āyurvedic health management, Sāṃkhya-Yoga epistemology, Haṭhayogic soteriology—wellbeing is understood not as the mere absence of disease but as the dynamic, cultivated alignment of physical health (ārogya), cognitive clarity (sattva-dominant buddhi), emotional integration (a well-functioning hṛdaya), and spiritual orientation toward liberation (mokṣa). This multi-dimensional model of flourishing, grounded in the concrete physiology of the mastiṣka–hṛdaya–nāḍī system and articulated through the Sāṃkhya Guṇa-antaḥkaraṇa framework, speaks directly to the science–religion–health dialogue that animates this Special Issue. It demonstrates that religious and contemplative traditions can generate empirically productive conceptual frameworks for understanding mind, body, and their mutual cultivation, while simultaneously offering normative resources for a vision of human wellbeing that transcends the limitations of biomedical reductionism. The Indian relational organ model, studied through the integrated lens of science, religion, and health, reveals itself as one of the most enduring and generative contributions that the Indian intellectual tradition offers to the global conversation about what it means, in the fullest sense, to flourish as a human being.

A final dimension of the article’s argument concerns the question of contemporary transformation: how have the practices analyzed here—Āyurvedic medicine, Haṭha Yoga, and Sāṃkhya-based contemplative training—evolved in response to the encounter with cognitive and neurological sciences? This question deserves more sustained attention than the present scope permits, but a provisional answer may be offered. Contemporary integrative medicine has selectively incorporated elements of Āyurvedic pharmacology, prāṇāyāma practice, and yogic posture into evidence-based therapeutic protocols—a process of translation that has generated genuine clinical insights alongside serious risks of decontextualization (Jain 2015; Alter 2004). What is notable, from the perspective of the present argument, is that this translation process has operated precisely along the structural lines identified in this article: it is the brain–heart–autonomic nervous system nexus—corresponding to the mastiṣka–hṛdaya–nāḍī model—that contemporary integrative medicine finds most clinically productive. The HRV (heart rate variability) research, the neuroimaging studies of meditation, and the autonomic effects of prāṇāyāma that this article has surveyed are not merely ‘confirmations’ of ancient wisdom; they are the outcomes of a genuine, if asymmetric, dialogue between living contemplative traditions and contemporary science. Practitioners in the Indian traditions have themselves been active participants in this dialogue: contemporary teachers within Yoga and Āyurveda increasingly incorporate neuroscientific vocabulary into their pedagogical frameworks, while leading researchers in contemplative neuroscience (Davidson and Lutz 2008; Thompson 2014) acknowledge the philosophical and practical resources that these traditions offer. This reciprocal engagement—in which the traditions are neither simply validated nor simply dismissed by science, but genuinely transformed through dialogue—is the mode of relationship that the present article has sought to model and to advocate.