- Development of the nervous system
2017-10-06 14:16:07
Today's Topics
Prenatal brain development
Insemination
- 3-4 days before or up to 1-2 days after…
- Ovulation
Fertilization
- Within ~ 24 hrs of ovulation
Implantation
- ~ 6 days after fertilization
Early embryogenesis
Formation of neural tube (neurulation)
- Embryonic layers: ectoderm, mesoderm, endoderm
- ~18-26 days
- Failures of neural tube closure
- Spina bifida
- Anencephaly
- Neural tube becomes
- Ventricles
- Central canal of spinal cord
Neurogenesis and gliogenesis
- Neuroepithelium cell layer lines neural tube
- Neural stem cells
- Undergo symmetric & asymmetric cell division
- Generate glia, neurons, and basal progenitor cells
Zika and microcephaly
Radial glia
Cell migration
Radial unit hypothesis
Migration
Migration
Glial migration
Axon growth cone
Axons follow
- Chemoattractants
- e.g., Nerve Growth Factor (NGF)
- Chemorepellents
- Receptors in growth cone detect chemical gradients
Differentiation
- Neuron vs. glial cell
- Cell type
- NTs released
- Where to connect
Differential gene expression in PFC vs. other
Infancy & Early Childhood
Synaptogenesis
Proliferation, pruning
- Early proliferation
- Later pruning
- Rates, peaks differ by area
Apoptosis
- Programmed cell death
- 20-80%, varies by area
- Spinal cord >> cortex
- Quantity of nerve growth factors (NGF) influences
Apoptosis and cortical expansion
Synaptic rearrangement
Synaptic rearrangement
- Progressive phase: growth rate >> loss rate
- Regressive phase: growth rate << loss rate
Myelination
Myelination
- Neonatal brain largely unmyelinated
- Gradual myelination, peaks in mid-20s
- Non-uniform pattern
- Spinal cord before brain
- Sensory before motor
Gyral development
Structural development
Postnatal patterns of synaptogenesis
Myelination across human development
Networks in the brain
Functional connectivity
- Age-related increases within visual-related areas (Petrican, Taylor, and Grady 2017)
The "development" of developmental connectomics
Myelination changes "network" properties
Synaptic rearrangment, myelination change cortical thickness
- (Gogtay et al. 2004)
- Areal differences in cortical thickness change
(Gogtay et al. 2004)
Changes in brain energetics
Gene expression across development
Summary of developmental milestones
Prenatal
- Neuro- and gliogenesis
- Migration
- Synaptogenesis begins
- Differentiation
- Apoptosis
- Myelination begins
- Infant gene expression ≠ Adult
Postnatal
- Synaptogenesis
- Cortical expansion, activity-dependent change
- Then cubic, quadratic, or linear declines in cortical thickness
- Myelination
- Connectivity changes (esp within networks)
- Prolonged period of postnatal/pre-reproductive development (Konner 2011)
How brain development clarifies anatomical structure
3-4 weeks
4 weeks
~4 weeks
6 weeks
~6 weeks
Beyond
Organization of the brain
| Major division | Ventricular Landmark | Embryonic Division | Structure |
|---|---|---|---|
| Forebrain | Lateral | Telencephalon | Cerebral cortex |
| Basal ganglia | |||
| Hippocampus, amygdala | |||
| Third | Diencephalon | Thalamus | |
| Hypothalamus | |||
| Midbrain | Cerebral Aqueduct | Mesencephalon | Tectum, tegmentum |
Organization of the brain
| Major division | Ventricular Landmark | Embryonic Division | Structure |
|---|---|---|---|
| Hindbrain | 4th | Metencephalon | Cerebellum, pons |
| – | Mylencephalon | Medulla oblongata |
From structural development to functional development
Next time…
- Perception
References
Cao, Miao, Hao Huang, and Yong He. 2017. “Developmental Connectomics from Infancy Through Early Childhood.” Trends in Neuroscience 40 (8): 494–506. doi:10.1016/j.tins.2017.06.003.
Chi, J G, E C Dooling, and F H Gilles. 1977. “Gyral Development of the Human Brain.” Ann. Neurol. 1 (1): 86–93. doi:10.1002/ana.410010109.
Gogtay, Nitin, Jay N Giedd, Leslie Lusk, Kiralee M Hayashi, Deanna Greenstein, A Catherine Vaituzis, Tom F Nugent, et al. 2004. “Dynamic Mapping of Human Cortical Development During Childhood Through Early Adulthood.” Proc. Natl. Acad. Sci. U. S. A. 101 (21): 8174–9. doi:10.1073/pnas.0402680101.
Götz, Magdalena, and Wieland B Huttner. 2005. “The Cell Biology of Neurogenesis.” Nat. Rev. Mol. Cell Biol. 6 (10): 777–88. doi:10.1038/nrm1739.
Hagmann, P., O. Sporns, N. Madan, L. Cammoun, R. Pienaar, V. J. Wedeen, R. Meuli, J.-P. Thiran, and P. E. Grant. 2010. “White Matter Maturation Reshapes Structural Connectivity in the Late Developing Human Brain.” Proceedings of the National Academy of Sciences 107 (44): 19067–72. doi:10.1073/pnas.1009073107.
Irimia, Andrei, and John Van Horn. 2014. “Systematic Network Lesioning Reveals the Core White Matter Scaffold of the Human Brain.” Frontiers in Human Neuroscience 8: 51. doi:10.3389/fnhum.2014.00051.
Johnson, Mark H. 2001. “Functional Brain Development in Humans.” Nat. Rev. Neurosci. 2 (7): 475–83. doi:10.1038/35081509.
Kang, Hyo Jung, Yuka Imamura Kawasawa, Feng Cheng, Ying Zhu, Xuming Xu, Mingfeng Li, André M M Sousa, et al. 2011. “Spatio-Temporal Transcriptome of the Human Brain.” Nature 478 (7370): 483–89. doi:10.1038/nature10523.
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Konner, Melvin. 2011. The Evolution of Childhood. Belknap Press of Harvard University Press. http://www.hup.harvard.edu/catalog.php?isbn=9780674062016.
Kuzawa, Christopher W, Harry T Chugani, Lawrence I Grossman, Leonard Lipovich, Otto Muzik, Patrick R Hof, Derek E Wildman, Chet C Sherwood, William R Leonard, and Nicholas Lange. 2014. “Metabolic Costs and Evolutionary Implications of Human Brain Development.” Proc. Natl. Acad. Sci. U. S. A. 111 (36): 13010–5. doi:10.1073/pnas.1323099111.
Petrican, Raluca, Margot J Taylor, and Cheryl L Grady. 2017. “Trajectories of Brain System Maturation from Childhood to Older Adulthood: Implications for Lifespan Cognitive Functioning.” Neuroimage, September. doi:10.1016/j.neuroimage.2017.09.025.
Rakic, Pasko. 2009. “Evolution of the Neocortex: A Perspective from Developmental Biology.” Nature Reviews Neuroscience 10 (10). Nature Publishing Group: 724–35.
Shaw, Philip, Noor J Kabani, Jason P Lerch, Kristen Eckstrand, Rhoshel Lenroot, Nitin Gogtay, Deanna Greenstein, et al. 2008. “Neurodevelopmental Trajectories of the Human Cerebral Cortex.” Journal of Neuroscience 28 (14). Soc Neuroscience: 3586–94. doi:10.1523/JNEUROSCI.5309-07.2008.