Zaidi: Neural Development Flashcards
Phase 1 neural development
Different cell types develop independently at separate locations
Phase 2 neural development
Axons and dendrites grow out along specific routes setting up provisional but orderly network of connections
Phase 3 neural development
Continues into adult life, connections are adjusted and refined through continued interactions
Neurons are produced in association with
Glial cells
CNS derived from
Neural tube
PNS derived from
Neural crest
What controls differentiation into neurons
Delta notch signaling (lateral inhibition and positive feedback)
Signals released from ventral and dorsal side of neural tube act as
Morphogens, causing neurons at different dorso-ventral positions to express different gene regulatory proteins
Neural crest cells originate at the _____ end of neural tube
Dorsal end
Fate of neural crest cells depends on
Where they migrate to and settle
What controls the movement of the growth cone on axons
Cytoskeletal machinery
GTPases Rho and Rac control the assembly/disassembly of actin filaments, which controls movement of growth cone
Projections from growth cone
Filopodia and lamelopodia
Major cues to help growth cones find their way
Extracellular matrix environment
Chemotactic factors- released by neighboring cells, can be attractive or repulsive
Contact guidance refers to
The tendency for growth cones to follow a path taken by other cells
Matrix molecules such as laminin favor
Axonal outgrowth
Matrix molecules such as chondroitin sulfate proteoglycans favor
Axon growth inhibition
Contact guidance is mediated by
Homophilic cell adhesion molecules:
- Immunoglobulin superfamily
- Cadherin family
Dorsal neurons of spinal cord
Receive and relay sensory information from sensory neurons
Ventral neurons of spinal cord
Develop as motor neurons and send out long axons to connect with muscles
First stage in guidance of commissural neurons
Secretion of netrin by cells of floor plate
Binding of netrin to its receptor causes
Opening of TRPC – allows entry of extracellular calcium
Entry of extracellular calcium leads to
Activation of machinery for extension of filopodia and movement of growth cone
(Non commissural neurons do not have netrin receptors, so they do not migrate towards floor plate)
Midline cells secrete _____ which does what, and what is the other similar molecule that is secreted
Slit
Commissural neurons have slit receptor (Roundabout)
Slit repels growth cones and blocks entry into midline
Semaphorin is another repulsive signa, but on the outside, which causes the growth cone to travel in a narrow track
What regulates which growth cones synapse and where they synapse
Signals from target tissues
Neurotrophic factors
Target cell produces limited amount of specific neurotrophic factors needed for survival, axons that do not get enough undergo apoptosis
Nerve growth factor- receptor name and function
Tyrosine kinase
Promotes survival of specific sensory neurons and sympathetic neurons
Short term effect of NGF
Effect on growth cone and neurite extension. Effect is local, direct, rapid and independent of communication with cell body
Long term effect of NGF
Effect on cell survival. Mediated by its receptor, uptake into cells via endocytosis and stimulation of downstream signaling pathways
Synaptic remodeling dependent upon which 2 rules that create spacial order
Axons from cells in different regions of retina compete for tectal neurons
Axons from neighboring sites which are excited at the same time cooperate/collaborate to retain and strengthen synapses with tectal neurons
Posterior retinal neurons prefer _______
Anterior retinal neurons prefer____
Posterior retinal neurons prefer anterior tectal neurons
Anterior retinal neurons have no preference
Entry of calcium through glutamate receptor triggers
Lasting change in synaptic strength
Synapses are strengthened by external events that cause
2 or more neurons to be activated at the same time
“Neurons that fire together, wire together”
