L11, L12 Cell Survival and Death, Specificity and Synaptic Connections Flashcards
NGF is required for the survival of what?
sympathetic and DRG neurons in developing during the critical period - may be removed afterwards
what are neurotrophins ?
they help the neurons make their connections in the CNS
NGD is a member of this family
what are neurotrophins required for?
-Required for proliferation, differentiation and survival of neural crest cells.
what are neurotrophins provided by?
- Provided by the neurons and the mesenchymal tissues initially.
- Provided by their targets after maturation.
what is the neurotrophins low affinity receptor?
p75
what is the neurotrophins high affinity receptor?
Trk oncogene
what does activation of neurotrophins receptors lead to?
activation of Phospholipase C, PIP3, and MPA kinase cascade
neurotrophins may play a role in..?
curing Alzheimer’s
define apoptosis?
programmed cell death
what is the importance of apoptosis in neural development?
allows for sole innervations of motor units
growing neurons are competing for vital substance released by what?
the target - only one neuron can win!
how do axons sort themselves?
anterior-posterior manner - specificity based on repulsion
what is responsible for repulsion of axons?
ephrin family of tyrosine kinases
what is the role of ephrin?
ephrin ligands repel each ether
- if ephrin is expressed in posterior tectum, the termporal ganglion cells (retinal) which also produce ephrin will repel eachother and make their connection with the anterior tectum instead
what does differential ephrin A2 and A5 expression allow?
for the gradients to provide proper pathways for retinal neuron growth.
skeletal motor end plates may have many neurons attached during when?
later embryonic development
synapses of skeletal motor neurons____ due to competition to leave the motoneuron with singular innervations
retract
The visual projections from the Lateral Geniculate Nucleus to the Visual Cortex are formed ______upon the visual experience in early life.
dependent
after development, the fibers of the visual projections bcome ____
myelinated - this is a period of plasticity in development
In a normally-developed visual system, the area of dominance columns for both eyes is the _____,
same
and each cortical cell responds to visual input according to its _____
column
____ ______ during early life prevents this balance from developing, and the non-deprived eye assumes control of nearly all cortical cells.
Monocular deprivation
what does it indicate if columns are even on left and right?
normal
what does it indicate if larger column on one side ?
ocular dominance
When born, all cells of the cortex layer 4 are driven by ______
both eyes.
After 6 weeks, all cells of the cortex layer 4 are driven by ____
one eye
The ______are alternations of cells driven by the left and right eye respectively.
“columns”
how long is the critical period?
3 mo.
During this critical period, if one eye is close or has cataracts the ocular columns of that eye will ___.
shrink
Even if the cataract or closure is repaired after 3 months that eye will always fail to drive ____
cortical cells. (Cause depolarization)
