{ "fact_registry": { "B1": { "key": "moreno_jimenez_2019", "label": "Moreno-Jim\u00e9nez et al. 2019, Nature Medicine \u2014 primary research article: identified thousands of immature neurons in the dentate gyrus of healthy humans up to the 9th decade" }, "B2": { "key": "kempermann_2018", "label": "Kempermann et al. 2018, Cell Stem Cell \u2014 18-author consensus review: no reason to abandon the idea that adult-generated neurons contribute across the human life span" }, "B3": { "key": "llorens_martin_2021", "label": "Llorens-Mart\u00edn et al. 2021, Journal of Neuroscience \u2014 primary research article: demonstrates AHN is a robust phenomenon in the human hippocampus during physiological and pathologic aging" }, "A1": { "label": "Count of independent sources confirming adult neurogenesis in humans (rejecting the claim)", "method": "sum(confirmations) = 3", "result": "3" } }, "claim_formal": { "subject": "The human brain", "property": "generates new neurons in adulthood (adult hippocampal neurogenesis, AHN)", "operator": ">=", "operator_note": "The claim asserts that adult neurogenesis does NOT occur (zero occurrence). We DISPROVE it by counting independent peer-reviewed sources that directly confirm adult neurogenesis in humans. proof_direction='disprove': n_confirming counts sources REJECTING the claim (i.e., confirming AHN exists). If n_confirming >= 3 (threshold), claim_holds=True means the disproof succeeds => verdict=DISPROVED. The threshold of 3 independent sources was chosen as a conservative minimum for scientific consensus.", "threshold": 3, "proof_direction": "disprove" }, "claim_natural": "The human brain does not generate new neurons in adulthood.", "citations": { "B1": { "source_key": "moreno_jimenez_2019", "source_name": "Moreno-Jim\u00e9nez et al. 2019, Nature Medicine (PubMed abstract)", "url": "https://pubmed.ncbi.nlm.nih.gov/30911133/", "quote": "we identified thousands of immature neurons in the DG of neurologically healthy human subjects up to the ninth decade of life", "status": "verified", "method": "full_quote", "coverage_pct": null, "fetch_mode": "live", "credibility": { "domain": "nih.gov", "source_type": "government", "tier": 5, "flags": [], "note": "Government domain (.gov)" } }, "B2": { "source_key": "kempermann_2018", "source_name": "Kempermann et al. 2018, Cell Stem Cell (PMC)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC6035081/", "quote": "there is currently no reason to abandon the idea that adult-generated neurons make important functional contributions to neural plasticity and cognition across the human life span", "status": "verified", "method": "full_quote", "coverage_pct": null, "fetch_mode": "live", "credibility": { "domain": "nih.gov", "source_type": "government", "tier": 5, "flags": [], "note": "Government domain (.gov)" } }, "B3": { "source_key": "llorens_martin_2021", "source_name": "Llorens-Mart\u00edn et al. 2021, Journal of Neuroscience (PMC)", "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC8018741/", "quote": "adult neurogenesis is a robust phenomenon that occurs in the human hippocampus during physiological and pathologic aging", "status": "verified", "method": "full_quote", "coverage_pct": null, "fetch_mode": "live", "credibility": { "domain": "nih.gov", "source_type": "government", "tier": 5, "flags": [], "note": "Government domain (.gov)" } } }, "extractions": { "B1": { "value": "keyword confirmed", "value_in_quote": true, "quote_snippet": "we identified thousands of immature neurons in the DG of neurologically healthy " }, "B2": { "value": "keyword confirmed", "value_in_quote": true, "quote_snippet": "there is currently no reason to abandon the idea that adult-generated neurons ma" }, "B3": { "value": "keyword confirmed", "value_in_quote": true, "quote_snippet": "adult neurogenesis is a robust phenomenon that occurs in the human hippocampus d" } }, "cross_checks": [ { "description": "Independent source agreement: all three sources confirm adult neurogenesis in humans", "n_sources": 3, "n_confirming": 3, "agreement": true } ], "adversarial_checks": [ { "question": "Is there credible peer-reviewed evidence that adult human neurogenesis does NOT occur? (Sources supporting the claim.)", "verification_performed": "Searched: 'Sorrells 2018 adult neurogenesis humans no evidence'. Found: Sorrells et al. 2018 (Nature 555:377-381) concluded 'neurogenesis in the dentate gyrus does not continue, or is extremely rare, in adult humans' based on 17 post-mortem controls (18-77 years) and 12 epilepsy surgical resections. This is the strongest counter-evidence in the literature.", "finding": "The Sorrells 2018 finding is attributed by the field to a methodological artifact: postmortem delay (PMD). DCX (doublecortin), the key marker for immature neurons, degrades rapidly after death. Sorrells samples had PMDs up to 48 hours; Boldrini et al. 2018 (Cell Stem Cell) used PMDs \u226426 hours and found persistent neurogenesis. Moreno-Jim\u00e9nez et al. 2019 used tightly controlled PMDs (<4 hours) and found thousands of immature neurons per mm\u00b2. The 18-author Kempermann et al. 2018 consensus review explicitly addressed the Sorrells controversy and concluded adult neurogenesis persists. Sorrells 2018 does not break the proof: its negative result reflects tissue fixation problems, not the absence of adult neurogenesis.", "breaks_proof": false }, { "question": "Is adult neurogenesis confirmed only in rodents, not specifically in humans? (Species-specificity challenge.)", "verification_performed": "Searched: 'adult neurogenesis absent humans but present rodents species-specific'. Reviewed: Eriksson et al. 1998 (Nature Medicine) \u2014 first human study using BrdU incorporation in post-mortem cancer patients, confirmed new neurons in adult human dentate gyrus. Spalding et al. 2013 (Cell) \u2014 used radiocarbon (14C) retrospective birthdating, confirmed new neurons in adult human hippocampus independently of any immunohistochemical markers.", "finding": "Human-specific studies using three independent methodologies \u2014 BrdU labeling (Eriksson 1998), 14C retrospective birthdating (Spalding 2013), and controlled-PMD immunohistochemistry (Moreno-Jim\u00e9nez 2019, Llorens-Mart\u00edn 2021) \u2014 all confirm adult neurogenesis in humans. No species-specific exclusion argument is credible.", "breaks_proof": false }, { "question": "Could 'adulthood' be interpreted such that neurogenesis tapers off before conventional adult ages (e.g., only persisting into early 20s)?", "verification_performed": "Searched: 'adult neurogenesis human age range decline decades'. Reviewed Moreno-Jim\u00e9nez 2019 subject ages: 43\u201387 years. Reviewed Llorens-Mart\u00edn 2021 which states persistence 'until the 10th decade of human life'. Boldrini et al. 2018 (Cell Stem Cell) found neurogenesis in subjects up to age 79.", "finding": "Neurogenesis is confirmed in subjects aged 43\u201387 (Moreno-Jim\u00e9nez 2019) and up to the 10th decade (Llorens-Mart\u00edn 2021). Even under any reasonable definition of 'adulthood' (post-18, post-25, etc.), neurogenesis persists. This adversarial challenge fails.", "breaks_proof": false } ], "verdict": "DISPROVED", "key_results": { "n_confirming": 3, "threshold": 3, "operator": ">=", "claim_holds": true, "proof_direction": "disprove" }, "generator": { "name": "proof-engine", "version": "0.10.0", "repo": "https://github.com/yaniv-golan/proof-engine", "generated_at": "2026-03-28" }, "proof_py_url": "/proof-engine/proofs/the-human-brain-does-not-generate-new-neurons-in-a/proof.py" }