Flashcards in Developmental Neurobiology Deck (18):
What are three critical events in neural development? (also areas where things go wrong)
- neurulation (by 4 weeks)
- segmentation and cleavage (8 weeks)
- proliferation and mirgration (8wks - birth...and even into infancy)
What happens during neurulation?
- differentiation (neuroectoderm and neural crest)
- axes of symmetry (head, ass, front, back)
- signal molecular gradients
What event triggers formation of dorsoventral axis?
closure of neural tube
What contributes to dorsoventral patterning?
Chemical gradients, sonic hedgehog and BMPs
What segments are formed from neural tube from segmentation?
1.prosencephalon - hind brain (telencephalon, diencephalon)
2. mesencephalon (midbrain)
3. rhombencephalon (metencephalon/pons, myelencephalon/medulla)
What happens during the proliferation and migration phase?
- evolution of computational capacity
Defect in ANTERIOR neuropore results in....
anencephaly (MOST SEVERE FORM...not compatible with life)
encephalocele (brain inside sac coming out of head)
defect in POSTERIOR neuropore
meningomyelocele (spinal cord in sac, much worse)
meningocoele (just CSF in sac)
spina bifida occulta (posterior elements of vertebrae haven't fused...not the worst thing that can happen)
What are risk factors for neural tube defects?
Valproate (for seizure)
Retinoic acid (acne)
What is the Arnold Chiari malformation?
Kind of between neural tube and segmentation defect
Brainstem doesn't really form correctly (segmentation part)
Dandy Walker malformation
blockage of sites where CSF flows out of ventricle...CSF blows out into cerebellum
Defects of segmentation results in what spectrum of defects?
spectrum of disorders ranging from ok to severe, associated with trisomy 13 Patau's and trisomy 18, also sonic hedgehog...sporadic
Mildest form of holoprosencephaly?
lesion in arrhinencephaly = absence of olfactory bulbs and tracts
single eye facial defect resulting in bad hemispheric cleavage
Defects in proliferation and migration can result in...
lissencephaly and polymicroglia
aka "smooth brain"
neuronal migration disorder, mental retardation associated with seziures, several genetic etiologies