Developmental Neurobio

Question 1

How do single cell organisms compare to NS?

Answer 1

They are able to sense the exterior and interior and are able to produce a specific adaptive response to the sensory info

Question 2

How does multicellularity contribute to the formation of a NS?

Answer 2

Multicellularity causes and requires cell specialisation for the increased complexity requires increased control.

Question 3

What are the earliest forms of sensorymotor systems?

Answer 3

Found in sponges water circulation -> myocytes able to respond to stretch signals -> basic movement

Question 4

What levels of organisational complexity do hydras display?

Answer 4

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

Question 5

What characteristics does a flatworm NS have?

Answer 5

It shows segmential and bilateral symmetry
Gangliation in the cephalic region
Early cephalisation
Commissures for bilateral coordination
Fasciculation for incr nerve conduction velocity

Question 6

What are the first parts of a CNS that might have developped?

Answer 6

The Hypothalamus as a sensory centre above the mouth region(now soft palate) -> outeat your enemies principle -> hypot incr rep fitness

Question 7

What NS structures are observable on insects?

Answer 7

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)

Question 8

How does multicellularity contribute to the formation of a NS?

Answer 8

Multicellularity causes and requires cell specialisation for the increased complexity requires increased control.

Question 9

What are the earliest forms of sensorymotor systems?

Answer 9

Found in sponges water circulation -> myocytes able to respond to stretch signals -> basic movement

Question 10

What levels of organisational complexity do hydras display?

Answer 10

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

Question 11

What characteristics does a flatworm NS have?

Answer 11

It shows segmential and bilateral symmetry
Gangliation in the cephalic region
Early cephalisation
Commissures for bilateral coordination
Fasciculation for incr nerve conduction velocity

Question 12

What are the first parts of a CNS that might have developped?

Answer 12

The Hypothalamus as a sensory centre above the mouth region(now soft palate) -> outeat your enemies principle -> hypot incr rep fitness

Question 13

What NS structures are observable on insects?

Answer 13

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)

Question 14

What induces the dorsal neural crest and what does it do?

Answer 14

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)

Question 15

What induces the ventral floorplate?

Answer 15

The Shh morphogens secreted by the notochord give ventral identity. In high conc they induce the floorplate

Question 16

What gives the different identities to the emerging neurons/progenitor cells in the neural tube?

Answer 16

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

Question 17

Why is are the hedgehog genes named like that?

Answer 17

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

Question 18

What regions of the NS is Shh expressed?

Answer 18

Hind and forebrain nd ventral side of neural tube
Responsible for hemisphere splitting (if not cyclopia and other unification)
Pit gland -> growth, appetite reg

Question 19

How does the neural tube get thicker?

Answer 19

The neural progenitors migrate and multiply

Question 20

What neurons emerge from dorsal progenitors?

Answer 20

Sans and Pans ganglion cells and neurons for each dermatome

Question 21

What neurons emerge from the ventral progenitor cells?

Answer 21

Motorneurons for every segment/dermatome

Question 22

What genes are needed to induce motorneuron fate?

Answer 22

Nix6.1, oligo2, Pax6

Question 23

How do slightly diff motoneurons devo, when they primarily need the same Shh conc

Answer 23

Intersected with Hox gradient and other signals encountered while migrating

Question 24

What are the two theories regarding axon growth?

Answer 24

Weiss: resonabce theory
Lots of growth randomly, weed out eventually
Sperry: chemoattraction
Axons receive signals

Question 25

What can be used for axona, guidance

Answer 25

Diffusable signals
Axons of other neurons
Cue cells that axon recognises on path and follows in growth

Question 26

Types of guidance cues are:

Answer 26

Chemoattraction
Chemorepellant
Contact attraction
Contact repellant

Question 27

Who discovered growth cones on axons?

Answer 27

Caja

Question 28

What experiments proove Sperry’s theory on axon growth?

Answer 28

Removal of temporal and nasal nerves on frog eyes-> regrowth to tectum the right way
Motor axon growrh on chick embryo after spinal segment has been flipped-> connect to right destination
Removal of other neurons in grasshopper embryo -> no right turns made when guidance axon not there

Question 29

What is the labelled pathway hypothesis?

Answer 29

That axons selectively fasciculate with other axons -> aka there are pioneer axons that other axons follow in growth (scaffold)

Question 30

What guidance do pioneer cells follow?

Answer 30

In a featureless environment” they orient themselves after ‘guidepost cells’ that are not secreting anything or morphologically really different, but removing them results in loss of axonal growth.
Other: boundaries of expressed tf-s