1.2.3 Neurodevelopment Flashcards
What is occuring during neurulation
The neural plate changes and neural folds develop at the lateral margins. The neural folds begin moving toward each other, forming the neural groove on the dorsal surface of the embryo. Eventually the neural plate cells pinch off to form the neural tube
What do the targets of neurons produce in order to influence development?
Trophic factors
Where is the alar plate? What is its function?
Dorsal; sensory
What is being shown in these radiolabeled images?
Synapse elimination
What is useful in reducing the number of cases of spina bifida?
Folic acid supplementation
As regional brain development continues, what does the mesencephalon (midbrain) go on to form?
cerebral aqueduct
Describe the closure process of the neural folds that end up forming the neural tube
The apposition of the neural folds to become the neural tube occurs first in the middle of the embryo and extends rostrally and caudally. The rostral and caudal neuropores are openings at each end of the developing neural tube
What fails to occur in spina bifida?
Failure of the caudal neuropore to close
How does the spinal cord mature during development?
As post-mitotic neurons leave the proliferative zone, the mantle layer layer increases in size. This region will become the gray matter of the spinal cord (dorsal and ventral horns).
The outermost layer of the spinal cord (white matter) is composed of the axons of local neurons within the gray matter as well as axons from neurons carrying ascending and descending information.
The ventricular zone (proliferative zone; labeled matrix layer here) eventually shrinks in size as proliferation ceases. This region becomes the innermost ependymal layer that lines the central canal of the spinal cord.
As regional brain development continues, what does the proencephalon (forebrain) go on to form?
telencephalon and diencephalon
What is the basal plate? What is its function?
Ventral; motor
The embryonic ectoderm thickens to form what during induction?
The neural plate
What is the role of the radial glia cell?
It helps guides newly produced neurons from the ventricular zone to the surface of the cerebral cortex.
Once a neuron is “born” in the ventricular zone, it often must migrate over some distance to reach its final destination in the developing brain. Neurons use chemical cues, contact with other neurons or glial cells, and other physical aspects of potential pathways to guide their migration. The formation of correct connections between groups of neurons also requires precision; not only must the correct groups of neurons connect, but synapses must often be made only on specific cell types within a target zone or on specific regions of the recipient neuron (e.g. dendrites vs. neuronal soma). In some instances, neurons make connections early in development, when targets are in close proximity, and “reel out” processes as growth of surrounding structures pushes them apart. In other instances, neurons use chemical or physical cues to grow to a target and synapse on the correct postsynaptic partner. Pathways in which a known pattern of topographic connections are normally made, such as the projection of retinal ganglion cells onto central visual targets, are often chosen as model systems to study the factors involved in synapse formation. For example, electrical activity in afferent fibers has been shown to be important in making correct connections, especially in sensory systems. Although most connections within the CNS are made during development, modification of connections, or synaptic plasticity, can occur following damage to a particular projection or in the course of “learning”.
When does neurodevelopment begin?
As early as three weeks post conception (usually before the mother knows that she is pregnant)
As regional brain development continues, what does the rhombencephalon (hindbrain) go on to form?
cerebellum, pons and medulla
What is being shown in these golgi silver stains?
Maturation of cellular architecture and connectivity
Once a neuron has had its neuronal birthday, what layer of the neural tube does it leave? Where does it go?
It leaves the ventricular layer and comes to rest in the mantle (intermediate) zone
Where are the neural crest cells located and how do they migrate?
Located on the most dorsal side and migrate out ventrally
What are the two different stages of early neural tube specialization (vesicle stages)?
At 4 wks: 3-vesicle stage
At 5 wks: 5-vesicle stage
What are some indicators of spina bifida?
Screen w/ AFP, ultrasound, amniocentesis
X-ray, MRI, or CT to image spinal column and vertebrae
