- Review for Exam 2 on Wednesday
- Exam 2 on Friday
2017-10-09 08:34:45
Announcements
Today's Topics
- Development of the nervous system
Human brain development take homes
- Prenatal
- Neuro- and gliogenesis
- Migration
- Synaptogenesis begins
- Differentiation
- Apoptosis
- Myelination begins
Human brain development take homes
- Postnatal
- Further synaptogenesis, synaptic pruning
- Cortical expansion, then thinning
- Myelination
- Changes in network properties – connectivity among areas
Neuro- and gliogenesis
- Neuroepithelium cell layer lines neural tube
- Neural stem cells
- Undergo symmetric & asymmetric cell divisions
- Generate glia, neurons, and basal progenitor cells
Radial glia provide "scaffolding" for migrating cells
Cells migrate from ventricular zone and subventricular zone
Radial units determine how cortical areas specialize?
Illustration of neural migration
Another illustration of migration
Glial cells also migrate (radially and longitudinally)
Illustration of axon growth cone
Axons growth cones follow chemical signals
- Receptors detect chemical gradients
- Chemoattractants
- e.g., Nerve Growth Factor (NGF)
- Chemorepellents
Cells differentiate
- Neuron vs. glial cell
- Cell type
- NTs released
- Where to connect
Synapses form (synaptogenesis)…
Programmed cell death (apoptosis)
- 20-80% of cells
- Varies by area
- Spinal cord >> cortex
- Quantity of nerve growth factor (NGF) received influences
Apoptosis and cortical expansion
Myelination occurs over extended period
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
Synaptic rearrangement occurs throughout life
- Progressive phase: growth rate >> loss rate
- Regressive phase: growth rate << loss rate
Myelination across human development
Networks in the brain
Functional connectivity
- Age-related increases within visual-related areas (Petrican, Taylor, and Grady 2017)
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
The adolescent brain: Different but not 'deficient'
Grey matter patterns differ in adolescents with psychiatric disorders
Changes in 'gyrification'
Sex differences in timing?
(a) Total brain volume, (b) gray matter volume, (c) white matter volume, (d) lateral ventricle volume, (e) mid-sagittal area of the corpus callosum, and (f) caudate volume. (R. K. Lenroot et al. 2007)
Functional (activation) differences
- To faces
- Situations involving peer influence
- In situations involving evaluating relative risk
Things we don't fully understand
- How does structural change affect functional development?
- Synaptogenesis?
- Myelination?
- Functional connectivity or activity levels?
- Regional differences in "maturation" peaks?
- How do individual differences in brain structure or function influence behavior?
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 |
Next time…
- Review for Exam 2
References
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, and Paul M Thompson. 2010. “Mapping Gray Matter Development: Implications for Typical Development and Vulnerability to Psychopathology.” Brain Cogn. 72 (1): 6–15. doi:10.1016/j.bandc.2009.08.009.
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.
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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Lenroot, Rhoshel K, Nitin Gogtay, Deanna K Greenstein, Elizabeth Molloy Wells, Gregory L Wallace, Liv S Clasen, Jonathan D Blumenthal, et al. 2007. “Sexual Dimorphism of Brain Developmental Trajectories During Childhood and Adolescence.” Neuroimage 36 (4): 1065–73. doi:10.1016/j.neuroimage.2007.03.053.
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. doi:10.1038/nrn2719.
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.
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