Flashcards in Neurodevelopment Deck (15):
Critical events in neurodevelopment and timeline
1. Neurulation: done by 4 wks
2. Segmentation and cleavage: done by 8 wks
3. Proliferation and migration: 8 weeks-birth
Three major events occur in neurulation:
1. Differentiation: neuroectoderm and neural crest
2. Establish axes of symmetry: cephalic to caudal, ventral to dorsal
3. Signal molecule gradients
Closure of the neural tube results in formation of which axis?
What three segments form? And what do they split into?
1. Prosencephalon (forebrain)
- Telencephalon (basal ganglia, cortex)
- Diencephalon (thalamus, hypothalamus)
2. Mesencephalon (midbrain)
3. Rhombencephalon (hindbrain)
- Metencephalon (pons, cerebellum)
- Myelencephalon (medulla)
Three major events in proliferation & migration
1. Evolution of computational capacity
2. Neuroectodermal precursors
Which neural tube defects are involved with the anterior neuropore?
- Anencephaly (most severe)
Which neural tube defects are involved with the posterior neuropore?
- Spina bifida occulta (least severe)
Which neural tube defect involves both anterior and posterior neuropore?
Arnold chiari malformation
How can neural tube defects be detected in utero? Which neural tube defect cannot be detected in utero?
Measure maternal serum alpha fetaprotein (AFP) with confirmation of dysraphia by US
Spina bifida occulta
What are well-documented risk factors for neural tube defects
- Folate deficiency
- Retinoic acid administration for acne
- Valoproate for seizures
What is a Dandy Walker malformation
Segmentation/cleavage problem - Sites where CSF flow out of ventricle get blocked, blows hole in midline of cerebellum
What is Holoprosencephaly? What chromosomal defect is it associated with?
Spectrum of defects of segmentation between prosencephalon into telencephalic hemispheres
Trisomy 13 Patau's and trisomy 18
What is most minimal lesion of holoprosencephaly
Arrhinencephaly - "no nose brain"
What is most severe lesion of holoprosencephaly
Alobar holoprosencephaly with cyclopia and other midfacial defects