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The development of the nervous system in humans, or neural development or neurodevelopment involves the studies of embryology, developmental biology, and neuroscience to describe the cellular and molecular mechanisms by which the complex nervous system forms in humans, develops during prenatal development, and continues to develop postnatally.
Neural induction
During early embryonic development the ectoderm becomes specified to give rise to the epidermis (skin) and the neural plate. The conversion of undifferentiated ectoderm to neuro-ectoderm requires signals from the mesoderm.
At the onset of gastrulation presumptive mesodermal cells move through the dorsal blastopore lip and form a layer in between the endoderm and the ectoderm. These mesodermal cells that migrate along the dorsal midline give rise to a structure called the notochord.
Ectodermal cells overlying the notochord develop into the neural plate in response to a diffusible signal produced by the notochord. The remainder of the ectoderm gives rise to the epidermis (skin). The ability of the mesoderm to convert the overlying ectoderm into neural tissue is called neural induction.
Late in the fourth week, the superior part of the neural tube flexes at the level of the future midbrain—the mesencephalon. Above the mesencephalon is the prosencephalon (future forebrain) and beneath it is the rhombencephalon (future hindbrain).
The optical vesicle (which will eventually become the optic nerve, retina and iris) forms at the basal plate of the prosencephalon.
The spinal cord forms from the lower part of the neural tube. The wall of the neural tube consists of neuroepithelial cells, which differentiate into neuroblasts, forming the mantle layer (the gray matter). Nerve fibers emerge from these neuroblasts to form the marginal layer (the white matter).
The ventral part of the mantle layer (the basal plates) forms the motor areas of the spinal cord, whilst the dorsal part (the alar plates) forms the sensory areas.
Between the basal and alar plates is an intermediate layer that contains neurons of the autonomic nervous system.
Early adulthood (also called "young adulthood") is a stage of life between 18 and 25 years, when grown ups become more independent and explore different life possibilities. Early adulthood or young adulthood may also refer to: Young adulthood stage in Erik Erikson's model between early and middle adulthood.
Brain Maturity Extends Well Beyond Teen Years : NPR. Brain Maturity Extends Well Beyond Teen Years Under most laws, young people are recognized as adults at age 18. But emerging science about brain development suggests that most people don't reach full maturity until the age 25
the nervous system fully developed at 15 years of age.
The speed of neural processing increases dramatically during infancy and childhood, reaching its maximum at about age 15.