Neural development Flashcards
Development of the neural tube
During the 1st month of gestation, humans undergo the process of neurulation, where chordates develop a dorsal nerve cord.
Area of ectoderm cells on the dorsal surface of the embryo develops into the neural plate.
Cells in neural plate change shape, plate folds inwards forming a groove along the back of the embryo, then separates from the rest of the ectoderm.
This forms the neural tube which elongates as the embryo grows.
development of neurons
Initially produced by differentiation in the neural tube.
The neural plate develops into the neural tube with continued proliferation of cells by mitosis and differentiation along pathways leading to the cells becoming functioning neurons.
Spina bifida
Incomplete closure of the embryonic neural tube can cause spina bifida.
Tissue migrates from both sides of the centrum around the neural tube and normally meets up the vertebral arch.
Sometimes the two parts of the arch never become properly fused together, leaving a gap: AKA spina bifida.
Most common in lower back.
Migration of neurons
Immature neurons migrate to a final location.
The cytoplasm and organelles are moved from the trailing end of the neurons to the leading edge by contractile actin filaments.
Migration of neurons is important in brian development.
Some neurons produced in one part of the brain migrate to another part where they find their final position.
Mature, functional neurons normally do not move, though their axons and dendrites re-grow if damaged.
Development of axons
an axon grows from each immature neuron in response to chemical stimuli.
Growth of axons
Some axons extend beyond the neural tube to reach other parts of the body.
Development of synapses
A developing neuron forms multiple synapses.
growth of an axon/ dendrite is directed so it can reach a cell it interacts with. Then a synapse is developed between the neuron and the other cell.
Elimination of synapses
Synapses that are not used do not persist.
use it or lose it
Neural pruning
Neural pruning involves the loss of unused neurons.
unused neurons destroy themselves by apoptosis.
Plasticity of the nervous system.
The plasticity of the nervous system allows it to change with experience.
connections between neurons can be changed by:
the growth of axons and dendrites,
by the establishment of new synapses,
by the elimination of synapses and pruning of dendrites, branches of axons or even whole neurons.
The stimulus for a change in the connections between neurons comes from the experiences of a person thus how their nervous system is used.
