Developmental Neurobio Flashcards
How do single cell organisms compare to NS?
They are able to sense the exterior and interior and are able to produce a specific adaptive response to the sensory info
How does multicellularity contribute to the formation of a NS?
Multicellularity causes and requires cell specialisation for the increased complexity requires increased control.
What are the earliest forms of sensorymotor systems?
Found in sponges water circulation -> myocytes able to respond to stretch signals -> basic movement
What levels of organisational complexity do hydras display?
Development of different neuron types from the same ectoderman ancestor
Formation of motorneuron circuits to effector cells
Incorporation of interneurons to
-> complex circuits computing different inputs and outputs
-> modulate by INHI and EXCI neurotransmitters
What characteristics does a flatworm NS have?
It shows segmential and bilateral symmetry
Gangliation in the cephalic region
Early cephalisation
Commissures for bilateral coordination
Fasciculation for incr nerve conduction velocity
What are the first parts of a CNS that might have developped?
The Hypothalamus as a sensory centre above the mouth region(now soft palate) -> outeat your enemies principle -> hypot incr rep fitness
What NS structures are observable on insects?
Devo of optic region close to eye and hypothalamus
Ventral NS
Neurons devo by delaminationg inside body -> conserve stem cell-like quality when forming neurons (ie Neuroblast remains)
How does multicellularity contribute to the formation of a NS?
Multicellularity causes and requires cell specialisation for the increased complexity requires increased control.
What are the earliest forms of sensorymotor systems?
Found in sponges water circulation -> myocytes able to respond to stretch signals -> basic movement
What levels of organisational complexity do hydras display?
Development of different neuron types from the same ectoderman ancestor
Formation of motorneuron circuits to effector cells
Incorporation of interneurons to
-> complex circuits computing different inputs and outputs
-> modulate by INHI and EXCI neurotransmitters
What characteristics does a flatworm NS have?
It shows segmential and bilateral symmetry
Gangliation in the cephalic region
Early cephalisation
Commissures for bilateral coordination
Fasciculation for incr nerve conduction velocity
What are the first parts of a CNS that might have developped?
The Hypothalamus as a sensory centre above the mouth region(now soft palate) -> outeat your enemies principle -> hypot incr rep fitness
What NS structures are observable on insects?
Devo of optic region close to eye and hypothalamus
Ventral NS
Neurons devo by delaminationg inside body -> conserve stem cell-like quality when forming neurons (ie Neuroblast remains)
What induces the dorsal neural crest and what does it do?
by BMPs and other trinduces by tfs produced in response to Msx and BMP signalling (Fgfs and wnts induce Pax activation)
Neural crest cells migrate away and become powerful progenitor cells that form the PNS and other important systems (sm muscle, adiposites, chondrocytes etc)
What induces the ventral floorplate?
The Shh morphogens secreted by the notochord give ventral identity. In high conc they induce the floorplate
What gives the different identities to the emerging neurons/progenitor cells in the neural tube?
Two morphogen gradients, the BMP/Wnt gradient secreted by the roofplate and the Shh gradientsecreted by the floorplate give in in combination.
The specific combination of the two makes the progenitors turn on the matching Pax genes
Why is are the hedgehog genes named like that?
When the drosophilia swith this mutation survives to adulthood it looks shriveled and spiky
When a series of genes was discovered in homologues, there were more and got named after species of hedgehogs - unfortunately by the time they reached the human ones, they ran out of names, hence fing sonic
What regions of the NS is Shh expressed?
Hind and forebrain nd ventral side of neural tube
Responsible for hemisphere splitting (if not cyclopia and other unification)
Pit gland -> growth, appetite reg
How does the neural tube get thicker?
The neural progenitors migrate and multiply
What neurons emerge from dorsal progenitors?
Sans and Pans ganglion cells and neurons for each dermatome
What neurons emerge from the ventral progenitor cells?
Motorneurons for every segment/dermatome
What genes are needed to induce motorneuron fate?
Nix6.1, oligo2, Pax6
How do slightly diff motoneurons devo, when they primarily need the same Shh conc
Intersected with Hox gradient and other signals encountered while migrating
What are the two theories regarding axon growth?
Weiss: resonabce theory
Lots of growth randomly, weed out eventually
Sperry: chemoattraction
Axons receive signals
