A comparative design brief for housing a living human brain in a synthetic body — for lifespan extension and space exploration. Grounded in 2026 technology and active laboratory research.
Author: Pitarn Rungsiyapornratana · ORCID 0009-0004-6411-2201
Current version: V1.4 · License: CC-BY-4.0 (see LICENSE)
DOI (concept, always latest): 10.5281/zenodo.20834976
An engineering design brief comparing three architectures for keeping a real, biological human brain alive and active inside a synthetic body. It is a speculative-but-grounded document: established science is the load-bearing spine; every non-trivial claim carries an epistemic tag; nothing that contradicts physics or measured data is asserted without being flagged.
It is not a brain-in-a-jar concept. The brain is embodied and actively used — the body feeds it sensory input, and (in the near-term path) a retained brainstem drives sleep and autonomic function.
- A — Conservative: brain + brainstem + full spinal cord; peripheral-nerve interfaces; highest technology-readiness, largest life-support.
- B — Balanced: brain + brainstem; spinal cord removed; BCI + neuromorphic reflex bypass.
- C — Aggressive: brain only in a perfusion vessel; everything via BCI; autonomic function emulated — the largest technology gap.
A Phase 1 → 3 roadmap starts with a real brainstem (A/B) and develops an artificial brainstem in parallel before any transition to C.
The engineering problems are largely solved or de-risked. What remains is biology, in two distinct forms:
- Acute — long-term brain perfusion. BrainEx (Vrselja & Sestan, Nature 2019) sustains an isolated brain for ~6 hours; a real system needs years. This cannot be engineered around — it must be solved at the tissue level.
- Chronic — neuron senescence. Even with perfect perfusion, post-mitotic neurons age, and identity-bearing neurons cannot be replaced (connectome + identity wall). This caps lifespan independently of perfusion.
Radiation is engineering-tractable but more than a thick wall: it needs hydrogen-rich, dose-optimized shielding (cosmic-ray secondary showers) plus independently rad-hardened compute.
synthetic_body_design_V1.4.pdf— rendered, with color-coded epistemic tags. Start here.synthetic_body_design_V1.4.md— Markdown source (single source of truth).synthetic_body_design_V1.4.docx— Word version.
| Tag | Meaning |
|---|---|
[ESTABLISHED] |
Tested / peer-reviewed; in clinical or engineering use today |
[THEORETICAL] |
Plausible basis, not yet experimentally confirmed |
[CONTESTED] |
Actively debated; no scientific consensus |
[MINORITY VIEW] |
Held by a small fraction of the relevant field |
[HYBRID SYNTHESIS] |
Combines or adapts existing ideas from named sources |
[SPECULATIVE] |
Beyond current science; needs a paradigm not yet in hand |
[USER'S OWN] |
A design decision or framing originated by the author |
Established science is credited to its originators by name (e.g. BrainEx — Vrselja & Sestan; sensory substitution — Bach-y-Rita, Eagleman; osseointegration — Brånemark; RPNI — Cederna & Kung). Recombinations of prior work are marked [HYBRID SYNTHESIS]. The author's name is attached only to genuine originations and design decisions. The full provenance table is in the Appendix of the document.
§9 records both why each chosen path was chosen (Adopted paths table) and why each alternative was cut (Rejected & superseded options, 18 entries) — so settled questions are not re-litigated.
See CITATION.cff. Version history is in CHANGELOG.md.
This is an independent theoretical/engineering brief, not a peer-reviewed publication or a buildable specification. It is shared for discussion and critique.