Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Development of the nervous system in humans
open-in-new
<p>The development of the nervous system in humans, or neural development, or neurodevelopment involves the studies of <a href="/facts/Embryology/4mvpSkhC">embryology</a>, <a href="/facts/Developmental_biology/9dLJhCCv">developmental biology</a>, and <a href="/facts/Neuroscience/o5RV8Cas">neuroscience</a>. These describe the cellular and molecular mechanisms by which the complex <a href="/facts/Nervous_system/CDxRKU2U">nervous system</a> forms in humans, develops during <a href="/facts/Prenatal_development/VpV3S4lu">prenatal development</a>, and continues to develop postnatally. </p><p>Some landmarks of neural development in the <a href="/facts/Embryo/9QHnLVLN">embryo</a> include: </p> <ol><li>The formation and <a href="/facts/Cellular_differentiation/bCVqUG7w">differentiation</a> of <a href="/facts/Neuron/G7CyTVdH">neurons</a> from <a href="/facts/Stem_cell/qgB9dFrI">stem cell</a> precursors (<a href="/facts/Neurogenesis/XSteTv8s">neurogenesis</a>)</li> <li>The <a href="/facts/Cellular_migration/5ySAMquQ">migration</a> of immature neurons from their birthplaces in the embryo to their final positions.</li> <li>The outgrowth of <a href="/facts/Axon/5DCd4wLo">axons</a> from neurons and the <a href="/facts/Axon_guidance/c33o0dQx">guidance</a> of the motile <a href="/facts/Growth_cone/UdspUDul">growth cone</a> through the embryo towards postsynaptic partners.</li> <li>The generation of <a href="/facts/Synapse/vdMRJCUn">synapses</a> between axons and their postsynaptic partners.</li> <li>The <a href="/facts/Synaptic_pruning/H39FHLqe">synaptic pruning</a> that occurs in <a href="/facts/Adolescence/XUkTHFyd">adolescence</a>.</li> <li>The lifelong <a href="/facts/Synaptic_plasticity/rdVFxItN">changes in synapses</a> which are thought to underlie learning and memory.</li></ol> <p>Typically, these neurodevelopmental processes can be broadly divided into two classes: </p> <ol><li>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 <a href="/facts/Cellular_differentiation/bCVqUG7w">differentiation</a>, <a href="/facts/Cellular_migration/5ySAMquQ">migration</a>, and <a href="/facts/Axon_guidance/c33o0dQx">axon guidance</a> to their initial target areas. These processes are thought of as being independent of neural activity and sensory experience.</li> <li>Activity-dependent mechanisms. Once <a href="/facts/Axon/5DCd4wLo">axons</a> reach their target areas, activity-dependent mechanisms come into play. Neural activity and sensory experience will mediate formation of new <a href="/facts/Synapses/vdMRJCUn">synapses</a>, as well as <a href="/facts/Synaptic_plasticity/rdVFxItN">synaptic plasticity</a>, which will be responsible for refinement of the nascent neural circuits.</li></ol>