06 Differentiation of Neurons

neuroepithelium: successor of neural tube

proliferating cells retract to ventricular surface: ventricular zone

-> postmitotic cells migrate to surface

from lower to higher layer - from ventricular zone (lumen) to marginal zone (pia)

ventricular zone: apical progenitors - radial glia: projecting climbing poles upwards

intermediate layer (?): extra type of neurons in humans and ferrets to produce larger number of neurons

time of birth of cortical neurons determines in which layer of adult brain the respective neuron will be positioned

neurons periventricular zone

tracts go upwards -> whiote matter outside

hemispheres

gyri

from medial and lateral ganglionic eminence

• between thalamus and ncl caudatus

• MGE: cortex

  • potential epilepsy treatment with interneuron progenitors from MGE in hippocampus? in mice

• LGE: olfactory bulb

• other option caudal GE

GABAergic and non-GABAergic interneurons

• e.g. parvalbumin-positive interneurons in neocortex (GABA)

• non-GABA: dopaminergic interneurons in olfactory bulb or cholinergic interneurons in striatum

primates and humans: second wave of interneurons from ventricular zone (later)

• not in mice - here only from eminences

medulla

thalamus

cerebellum

colliculus superior

widespread through brain but extremely focused projections

growth cones

• lamellae and filopedia

actin cycle

• actin depolymerization at proximal end, polymerization at distal end

• actin monomers are continuously recycled to the front

• laminin, fibronectin, surface molecules: for advancement of grwoth cones

  • attractors and repulsors

guidance to: cells, axons, guidepost cells, anatomical landmarks

grid-like fibre pathways in primates

semaphorin guides initial growth of cortical pyramidal axons

same odorent receptor inputs merge in respective glomeruli

sema-1a global graded determinantes + global cues sema2a/b

• find glomeruli - gradients

local discrete determinantes

• gradients of receptors

dendrite-axon matching molecules

• axons find transmembrane proteins to merge in glomerulus