Human development · Lesson + lab

Human Development: The Neuron Lab

Every thought, feeling and behavior travels through neurons. Learn how the nervous system is organized, build a neuron piece by piece, send a signal across the synapse, and see how the brain is built and rewired from before birth to old age.

Part 1 · The big picture

How the nervous system is organized

Tap any branch. The neuron you build below is the basic unit of every part of this map¹².

Selected

Nervous system

All the neurons and glia of the body, divided into central and peripheral parts.

Part 2 · Interactive lab

Build a neuron

Drag each part onto its dashed outline (or tap a part, then tap where it goes). Each correct placement explains what the part does and how it connects to the brain and the next neuron. When the neuron is complete, fire it and watch the signal cross the synapse.

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Start with the dendrites, the neuron's receivers, or with any part you know.

Part info

Pick a part

Explanations appear here as you build.

Part 3 · The other half of the brain

Glia: the builders and caretakers

Glia make up roughly half the cells of the central nervous system. They were once thought to be passive "glue," but they guide neuron birth and migration, build myelin and shape synapses³⁴.

Astrocytes

The most abundant glia. They help form, maintain and remodel synaptic connections and talk back and forth with neurons⁵.

Oligodendrocytes & Schwann cells

Wrap axons in myelin (CNS and PNS respectively) and supply axons with energy⁶².

Microglia

The brain's immune cells. During development they help remove unneeded synapses, guided by neural activity⁷.

Part 4 · Development across the lifespan

How the brain is built — and rebuilt

Slide through the lifespan. Development is not only growth: it is growth, pruning and insulation, in a set order from sensory areas to the prefrontal cortex⁸.

PrenatalBirth to 2 yearsEarly childhoodChildhood–adolescenceAdolescenceLate 20sAdulthoodOlder adulthood

Bars are a simplified illustration of the shape of published growth curves⁹, not exact values.

Part 5 · Nature and nurture

Experience shapes the developing brain

Threat vs. deprivation

A review of 109 MRI studies found children exposed to threat (such as violence) tended to show changes in the amygdala, hippocampus and medial prefrontal cortex, while children exposed to deprivation (such as neglect) showed changes in frontoparietal regions¹⁰.

Poverty

Poverty can shape the developing brain through less cognitive stimulation, poor nutrition, stress and toxins — but outcomes vary widely and are not destiny¹¹.

Enrichment

Stimulating environments increase new neuron growth in the hippocampus in animal studies and create individual differences in plasticity¹².

Why it matters for educators

Because association areas stay plastic for so long, adolescence and young adulthood are windows for learning and for support — and for vulnerability to mental health conditions¹³⁸.

Next: Synapse to Symptom — what happens at the gap in mental health conditions →

Practice

Flashcards and games

References

Peer-reviewed sources (22)

All 22 sources are peer-reviewed and published 2016 or later; each was checked against its PubMed record. The neuron drawing is an original simplified illustration, not to scale.

1
2016Peer-reviewedLast 10 years
Wehrwein, E. A., Orer, H. S., & Barman, S. M. (2016). Overview of the anatomy, physiology, and pharmacology of the autonomic nervous system. Comprehensive Physiology, 6(3), 1239–1278. https://doi.org/10.1002/cphy.c150037
2
2018Peer-reviewedLast 10 years
Stassart, R. M., Möbius, W., Nave, K.-A., & Edgar, J. M. (2018). The axon-myelin unit in development and degenerative disease. Frontiers in Neuroscience, 12, Article 467. https://doi.org/10.3389/fnins.2018.00467
3
2018Peer-reviewedLast 10 years
Allen, N. J., & Lyons, D. A. (2018). Glia as architects of central nervous system formation and function. Science, 362(6411), 181–185. https://doi.org/10.1126/science.aat0473
4
2016Peer-reviewedLast 10 years
von Bartheld, C. S., Bahney, J., & Herculano-Houzel, S. (2016). The search for true numbers of neurons and glial cells in the human brain: A review of 150 years of cell counting. Journal of Comparative Neurology, 524(18), 3865–3895. https://doi.org/10.1002/cne.24040
5
2017Peer-reviewedLast 10 years
Allen, N. J., & Eroglu, C. (2017). Cell biology of astrocyte-synapse interactions. Neuron, 96(3), 697–708. https://doi.org/10.1016/j.neuron.2017.09.056
6
2019Peer-reviewedLast 10 years
Stadelmann, C., Timmler, S., Barrantes-Freer, A., & Simons, M. (2019). Myelin in the central nervous system: Structure, function, and pathology. Physiological Reviews, 99(3), 1381–1431. https://doi.org/10.1152/physrev.00031.2018
7
2021Peer-reviewedLast 10 years
Faust, T. E., Gunner, G., & Schafer, D. P. (2021). Mechanisms governing activity-dependent synaptic pruning in the developing mammalian CNS. Nature Reviews Neuroscience, 22(11), 657–673. https://doi.org/10.1038/s41583-021-00507-y
8
2021Peer-reviewedLast 10 years
Sydnor, V. J., Larsen, B., Bassett, D. S., Alexander-Bloch, A., Fair, D. A., Liston, C., Mackey, A. P., Milham, M. P., Pines, A., Roalf, D. R., Seidlitz, J., Xu, T., Raznahan, A., & Satterthwaite, T. D. (2021). Neurodevelopment of the association cortices: Patterns, mechanisms, and implications for psychopathology. Neuron, 109(18), 2820–2846. https://doi.org/10.1016/j.neuron.2021.06.016
9
2022Peer-reviewedLast 10 years
Bethlehem, R. A. I., Seidlitz, J., White, S. R., Vogel, J. W., Anderson, K. M., Adamson, C., Adler, S., Alexopoulos, G. S., Anagnostou, E., Areces-Gonzalez, A., Astle, D. E., Auyeung, B., Ayub, M., Bae, J., Ball, G., Baron-Cohen, S., Beare, R., Bedford, S. A., Benegal, V., . . . Alexander-Bloch, A. F. (2022). Brain charts for the human lifespan. Nature, 604(7906), 525–533. https://doi.org/10.1038/s41586-022-04554-y
10
2019Peer-reviewedLast 10 years
McLaughlin, K. A., Weissman, D., & Bitrán, D. (2019). Childhood adversity and neural development: A systematic review. Annual Review of Developmental Psychology, 1, 277–312. https://doi.org/10.1146/annurev-devpsych-121318-084950
11
2016Peer-reviewedLast 10 years
Johnson, S. B., Riis, J. L., & Noble, K. G. (2016). State of the art review: Poverty and the developing brain. Pediatrics, 137(4), Article e20153075. https://doi.org/10.1542/peds.2015-3075
12
2019Peer-reviewedLast 10 years
Kempermann, G. (2019). Environmental enrichment, new neurons and the neurobiology of individuality. Nature Reviews Neuroscience, 20(4), 235–245. https://doi.org/10.1038/s41583-019-0120-x
13
2018Peer-reviewedLast 10 years
Larsen, B., & Luna, B. (2018). Adolescence as a neurobiological critical period for the development of higher-order cognition. Neuroscience & Biobehavioral Reviews, 94, 179–195. https://doi.org/10.1016/j.neubiorev.2018.09.005
14
2016Peer-reviewedLast 10 years
Silbereis, J. C., Pochareddy, S., Zhu, Y., Li, M., & Sestan, N. (2016). The cellular and molecular landscapes of the developing human central nervous system. Neuron, 89(2), 248–268. https://doi.org/10.1016/j.neuron.2015.12.008
15
2020Peer-reviewedLast 10 years
Runge, K., Cardoso, C., & de Chevigny, A. (2020). Dendritic spine plasticity: Function and mechanisms. Frontiers in Synaptic Neuroscience, 12, Article 36. https://doi.org/10.3389/fnsyn.2020.00036
16
2018Peer-reviewedLast 10 years
Leterrier, C. (2018). The axon initial segment: An updated viewpoint. The Journal of Neuroscience, 38(9), 2135–2145. https://doi.org/10.1523/JNEUROSCI.1922-17.2018
17
2020Peer-reviewedLast 10 years
Cohen, C. C. H., Popovic, M. A., Klooster, J., Weil, M.-T., Möbius, W., Nave, K.-A., & Kole, M. H. P. (2020). Saltatory conduction along myelinated axons involves a periaxonal nanocircuit. Cell, 180(2), 311–322.e15. https://doi.org/10.1016/j.cell.2019.11.039
18
2018Peer-reviewedLast 10 years
Rizo, J. (2018). Mechanism of neurotransmitter release coming into focus. Protein Science, 27(8), 1364–1391. https://doi.org/10.1002/pro.3445
19
2021Peer-reviewedLast 10 years
Südhof, T. C. (2021). The cell biology of synapse formation. Journal of Cell Biology, 220(7), Article e202103052. https://doi.org/10.1083/jcb.202103052
20
2023Peer-reviewedLast 10 years
Mısır, E., & Akay, G. G. (2023). Synaptic dysfunction in schizophrenia. Synapse, 77(5), Article e22276. https://doi.org/10.1002/syn.22276
21
2017Peer-reviewedLast 10 years
Biederer, T., Kaeser, P. S., & Blanpied, T. A. (2017). Transcellular nanoalignment of synaptic function. Neuron, 96(3), 680–696. https://doi.org/10.1016/j.neuron.2017.10.006
22
2018Peer-reviewedLast 10 years
Mattson, M. P., & Arumugam, T. V. (2018). Hallmarks of brain aging: Adaptive and pathological modification by metabolic states. Cell Metabolism, 27(6), 1176–1199. https://doi.org/10.1016/j.cmet.2018.05.011