Neurogenesis and Migration Flashcards
Lissencephaly means ___________.
smooth brain (i.e., a brain without sulci)
Post-mitotic cells must ___________ a radial glia to __________. Any defect in the genes that encode for this can result in lissencephaly.
adhere to; migrate to the more superficial layers of the cortex
Reelin is involved in ___________.
migration in the cortex and the cerebellum
What cells secrete reelin?
Cajal-Retzius cells
__________ have a more severe phenotype of lissencephaly / double-cortex syndrome.
Males (because it is X-linked)
List three genes that, if disrupted, can lead to defects in cortical migration.
Reelin and LCH (getting off of the radial glia)
Filamin (getting on)
DCX and Lis1 (staying on the radial glia)
What is LCH?
Lissencephaly with cerebellar hypoplasia; a protein involved in getting off of the radial glia
What area of the nervous system has the opposite pattern of cortical migration (that is, opposite to the inside-out pattern)?
The retina; in the retina, the neurons migrate outside-in (with the distal-most cells migrating first)
What are neurotrophins?
Proteins that stimulate the growth of neurons – such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT-3, glia-derived neurotrophic factor (GDNF), and NT-4
To what type of receptors do neurotrophins bind?
Tropomyosin-related kinase (Trk)
Almost ________ percent of the Cajal-Retzius cells die during development.
100
Growth cones have ________ with a dense population of ___________.
filopodia; receptors
CAMs are _________. They work independently of calcium.
cell-adhesion molecules
Cytokines directing axonal migration can be repulsive or attractive depending on ______________.
the receptor it binds
In patients with a defective filamin protein, _________ cells accumulate in the ventricular zone.
differentiated (because the filamin protein helps differentiated cells migrate outward)
Mutations in LIS1 will produce ___________.
lissencephaly with epilepsy and mental retardation
Neurons born at the same time tend to ____________.
end up in the same layer
Cell death in most neurodegenerative diseases occurs by _____________.
apoptosis
What is the neurotrophic factor hypothesis?
The idea that neuron targets produce limited amounts of neurotrophic factors so that only the closest neuron will make a connection
Netrins can be _______ or __________.
attractive; repulsive
Semaphorins are always ____________.
repulsive
Cadherins, CAMs, laminin, and proteoglycans are usually __________ signals.
attractive
CNS oligodendrocytes express __________, thought to play a role in preventing axon growth.
Nogo
What neurogenic pattern is typical of autism spectrum disorders?
A brain small at birth followed by an abnormally high rate of growth resulting in disproportionately high content of white matter
In the CNS, myelination is first observed at the end of the ___________.
first trimester
How are GABA channels different in embryonic development?
The E(Cl) is less negative, so GABA channels actually depolarize the cell membrane during development!
