Timeline of human brain development

The human brain development timeline encompasses the sequential, overlapping phases in which the central nervous system forms, matures, and reorganizes from conception through adolescence and into early adulthood. This process starts in the third gestational week with the differentiation of neural progenitor cells and progresses through neurogenesis, cell migration, synaptogenesis, myelination, and synaptic pruning.

Many foundational structures of the brain, including the forebrain, midbrain, and hindbrain, emerge by the sixth week of gestation, with further differentiation resulting in secondary regions like the telencephalon, diencephalon, and metencephalon in subsequent weeks. Structural milestones, including the formation of cortical folds and the appearance of commissural fibers, occur rapidly during prenatal development.

Postnatally, white matter volume and grey matter architecture undergo significant changes, with cortical regions maturing at different rates. The frontal and parietal lobes tend to mature earlier than temporal regions, with synaptic pruning and myelination continuing into the fourth decade of life. Experience and environmental factors dynamically shape neural connectivity, influencing lifelong cognitive, affective, and behavioral outcomes.

Advances in magnetic resonance imaging and the study of brain organoids have enhanced understanding of neurological disorders and critical periods of vulnerability, enabling new approaches for early diagnosis and intervention.

Conception

Highlights of human brain development from conception through adulthood.
Day Event Reference
33posterior commissure appearsAshwell et al. (1996)
33medial forebrain bundle appearsAshwell et al. (1996)
44mammillothalamic tract appearsAshwell et al. (1996)
44stria medullaris thalami appearsAshwell et al. (1996)
51axons in optic stalkDunlop et al. (1997)
56external capsule appearsAshwell et al. (1996)
56stria terminalis appearsAshwell et al. (1996)
60optic axons invade visual centersDunlop et al. (1997)
63internal capsule appearsAshwell et al. (1996)
63fornix appearsAshwell et al. (1996)
70anterior commissure appearsAshwell et al. (1996)
77hippocampal commissure appearsAshwell et al. (1996)
87.5corpus callosum appearsAshwell et al. (1996)
157.5eye openingClancy et al. (2007)
175ipsi/contra segregation in LGN and SCRobinson & Dreher (1990)

Studies report that three primary structures are formed in the sixth gestational week. These are the forebrain, the midbrain, and the hindbrain, also known as the prosencephalon, mesencephalon, and the rhombencephalon respectively. Five secondary structures originate from these in the seventh gestational week. These are the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon; the lateral ventricles, third ventricles, cerebral aqueduct, and upper and lower parts of the fourth ventricle in adulthood originated from these structures. The appearance of cortical folds first takes place during 24 and 32 weeks of gestation.

Childhood and adolescence

Cortical white matter increases from childhood (~9 years) to adolescence (~14 years), most notably in the frontal and parietal cortices. Cortical grey matter development peaks at ~12 years of age in the frontal and parietal cortices, and 14–16 years in the temporal lobes (with the superior temporal cortex being last to mature), peaking at about roughly the same age in both sexes according to reliable data. In terms of grey matter loss, the sensory and motor regions mature first, followed by other cortical regions. Though it is a controversial psychometric, adult IQ also begins to be tested around this age range, with the Raven's Progressive Matrices test beginning at age 14 and the Wechsler Adult Intelligence Scale test beginning at age 16, though scores between 14 and 16 on the Wechsler test have differences so small that they are considered unreliable. This may bring into question the effectiveness of brain development studies in treating and successfully rehabilitating criminal youth.

In the 2010s and beyond, science has shown that the brain continues to develop until at least 30 years of age.

See also

References

  1. ↑ Tau, G.Z.; Peterson, B.S. (2010). "Normal Development of Brain Circuits". Neuropsychopharmacology. 35 (1): 147–168. doi:10.1038/npp.2009.115. PMC 3055433. PMID 19794405.
  2. 1 2 3 Moore, Andrew (2024). "Development and Maturation of the Human Brain, from Infancy to Adolescence". Handbook of Developmental Neuroscience. Current Topics in Behavioral Neurosciences. 68: 327–348. doi:10.1007/7854_2024_514. ISBN 978-3-031-70136-8. PMID 39138744.{{cite journal}}: CS1 maint: periodical has ISBN (link)
  3. ↑ Volpe, Joseph J. (2000). "Overview: Normal and abnormal human brain development". Mental Retardation and Developmental Disabilities Research Reviews. 6 (1): 1–5. doi:10.1002/(SICI)1098-2779(2000)6:1<1::AID-MRDD1>3.0.CO;2-J. ISSN 1098-2779. PMID 10899791.
  4. ↑ "What are the 7 Stages of Brain Development?". NeuroCenterNJ. 2024-06-22.
  5. ↑ "The Developing Brain". From Neurons to Neighborhoods. National Academies Press. 1999.
  6. ↑ Kim, M.S.; Jeanty, P.; Turner, C.; Benoit, B. (2008). "Three-dimensional sonographic evaluations of embryonic brain development". J Ultrasound Med. 27 (1): 119–124. doi:10.7863/jum.2008.27.1.119. PMID 18096737.
  7. ↑ Budday, Silvia; Raybaud, Charles; Kuhl, Ellen (2014). "A mechanical model predicts morphological abnormalities in the developing human brain". Scientific Reports. 4 (5644) 5644. Bibcode:2014NatSR...4.5644B. doi:10.1038/srep05644. PMC 4090617. PMID 25008163.
  8. ↑ Ashwell, K.W.; Waite, P.M.; Marotte, L. (1996). "Ontogeny of the projection tracts and commissural fibres in the forebrain of the tammar wallaby (Macropus eugenii): timing in comparison with other mammals". Brain, Behavior and Evolution. 47 (1): 8–22. doi:10.1159/000113225. PMID 8834781.
  9. 1 2 Blakemore, S.J. (2012). "Imaging brain development: the adolescent brain". NeuroImage. 61 (2): 397–406. doi:10.1016/j.neuroimage.2011.11.080. PMID 22178817.
  10. ↑ Ouyang, Ming; Jeon, Tae Hyun; Chung, Sungmin; Kim, Ji Hye; Huang, Hao (2018). "Delineation of early brain development from fetuses to infants with diffusion MRI and beyond". Front Neurosci. 12: 538. doi:10.3389/fnins.2018.00538. PMC 6185831. PMID 29997493.
  11. ↑ Shafee, R.; Buckner, R. L.; Fischl, B. (2014). "Gray matter myelination of 1555 human brains using partial volume corrected MRI images". NeuroImage. 105: 473–485. doi:10.1016/j.neuroimage.2014.10.054. PMC 4262571. PMID 25449739.
  12. ↑ Stiles, Joan; Jernigan, Terry L. (2010). "The Basics of Brain Development". Neuropsychology Review. 20 (5): 327–348. doi:10.1007/s11065-010-9148-4. PMC 2989000. PMID 20544222.
  13. ↑ Knickmeyer, Rebecca C.; Gouttard, Sylvain; Kang, Chaeryon; Evans, Dianne; Wilber, Kathy; Smith, J. Keith; Hamer, Robert M.; Lin, Weili; Gerig, Guido; Gilmore, John H. (2008-11-19). "A Structural MRI Study of Human Brain Development from Birth to 2 Years". Journal of Neuroscience. 28 (47): 12176–12182. doi:10.1523/JNEUROSCI.3479-08.2008. ISSN 0270-6474. PMC 2884385. PMID 19020011.
  14. ↑ Xu, Jie; Wen, Zhexing (2021). "Brain Organoids: Studying Human Brain Development and Diseases in a Dish". Stem Cells International: 1–16. doi:10.1155/2021/5902824. PMC 8448601. PMID 34539790.
  15. ↑ Budday, Silvia; Raybaud, Charles; Kuhl, Ellen (2014). "A mechanical model predicts morphological abnormalities in the developing human brain". Scientific Reports. 4 5644. Bibcode:2014NatSR...4.5644B. doi:10.1038/srep05644. PMC 4090617. PMID 25008163.
  16. ↑ Tau, G. Z.; Peterson, B. S. (2010). "Normal Development of Brain Circuits". Neuropsychopharmacology. 35 (1): 147–168. doi:10.1038/npp.2009.115. PMC 3055433. PMID 19794405.
  17. 1 2 3 4 5 6 7 8 9 10 11 Ashwell, K. W.; Waite, P. M.; Marotte, L (1996). "Ontogeny of the projection tracts and commissural fibres in the forebrain of the tammar wallaby (Macropus eugenii): timing in comparison with other mammals". Brain, Behavior and Evolution. 47 (1): 8–22. doi:10.1159/000113225. PMID 8834781.
  18. 1 2 Dunlop, S. A.; Tee, L. B.; Lund, R. D.; Beazley, L. D. (1997). "Development of primary visual projections occurs entirely postnatally in the fat-tailed dunnart, a marsupial mouse, nrnitnen". The Journal of Comparative Neurology. 384 (1): 26–40. doi:10.1002/(SICI)1096-9861(19970721)384:1<26::AID-CNE2>3.0.CO;2-N. PMID 9214538. S2CID 38381685.
  19. ↑ Clancy, B; Kersh, B; Hyde, J; Darlington, R. B.; Anand, K. J.; Finlay, B. L. (2007). "Web-based method for translating neurodevelopment from laboratory species to humans". Neuroinformatics. 5 (1): 79–94. doi:10.1385/ni:5:1:79. PMID 17426354. S2CID 1806001.
  20. ↑ Robinson, S. R.; Dreher, B (1990). "The visual pathways of eutherian mammals and marsupials develop according to a common timetable". Brain, Behavior and Evolution. 36 (4): 177–195. doi:10.1159/000115306. PMID 2279233.
  21. ↑ Kim MS, Jeanty P, Turner C, Benoit B (January 2008). "Three-dimensional sonographic evaluations of embryonic brain development". J Ultrasound Med. 27 (1): 119–24. doi:10.7863/jum.2008.27.1.119. PMID 18096737.
  22. ↑ Budday, Silvia; Raybaud, Charles; Kuhl, Ellen (2014-01-01). "A mechanical model predicts morphological abnormalities in the developing human brain". Scientific Reports. 4 5644. Bibcode:2014NatSR...4.5644B. doi:10.1038/srep05644. ISSN 2045-2322. PMC 4090617. PMID 25008163.
  23. 1 2 Blakemore, S.J. (June 2012). "Imaging brain development: the adolescent brain". NeuroImage. 61 (2): 397–406. doi:10.1016/j.neuroimage.2011.11.080. PMID 22178817. S2CID 207182527.
  24. ↑ Icenogle, G.; Steinberg, L.; Duell, N.; Chein, J.; Chang, L.; Chaudhary, N.; Di Giunta, L.; Dodge, K. A.; Fanti, K. A.; Lansford, J. E.; Oburu, P.; Pastorelli, C.; Skinner, A. T.; Sorbring, E.; Tapanya, S.; Tirado, L. M.; Alampay, L. P.; Al-Hassan, S. M.; Takash, H. M.; Bacchini, D. (2019). "Adolescents' Cognitive Capacity Reaches Adult Levels Prior to Their Psychosocial Maturity: Evidence for a "Maturity Gap" in a Multinational, Cross-Sectional Sample". Law and Human Behavior. 43 (1): 69–85. doi:10.1037/lhb0000315. PMC 6551607. PMID 30762417.
  25. ↑ Shafee, R.; Buckner, R. L.; Fischl, B. (2014). "Gray matter myelination of 1555 human brains using partial volume corrected MRI images". NeuroImage. 105: 473–485. doi:10.1016/j.neuroimage.2014.10.054. PMC 4262571. PMID 25449739.