Development of the nervous system in humans

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Development of the nervous system in humans" – news · newspapers · books · scholar · JSTOR (December 2023) (Learn how and when to remove this message)

The development of the nervous system in humans, or neural development, or neurodevelopment involves the studies of embryology, developmental biology, and neuroscience. These describe the cellular and molecular mechanisms by which the complex nervous system forms in humans, develops during prenatal development, and continues to develop postnatally.

Some landmarks of neural development in the embryo include:

1. The formation and differentiation of neurons from stem cell precursors (neurogenesis)
2. The migration of immature neurons from their birthplaces in the embryo to their final positions.
3. The outgrowth of axons from neurons and the guidance of the motile growth cone through the embryo towards postsynaptic partners.
4. The generation of synapses between axons and their postsynaptic partners.
5. The synaptic pruning that occurs in adolescence.
6. The lifelong changes in synapses which are thought to underlie learning and memory.

Typically, these neurodevelopmental processes can be broadly divided into two classes:

1. Activity-independent mechanisms. Activity-independent mechanisms are generally believed to occur as hardwired processes determined by genetic programs that are played out within individual neurons. These include differentiation, migration, and axon guidance to their initial target areas. These processes are thought of as being independent of neural activity and sensory experience.
2. Activity-dependent mechanisms. Once axons reach their target areas, activity-dependent mechanisms come into play. Neural activity and sensory experience will mediate formation of new synapses, as well as synaptic plasticity, which will be responsible for refinement of the nascent neural circuits.^{[citation needed]}