Development of neurotransmitters Flashcards
What 3 things does the nervous system vary in?
1) Types of cells
2) Chemical properties
3) Electrical properties
Why is variation in the nervous system important?
- Important to build complex circuits which can be optimised to do particular jobs
How is the spinal cord different to the neural tube?
- Looks different
- Multiple layers, which have migrated away from the developing neural tube
Where do afferents from the DRG target in the spinal cord?
Different layers, depending upon what the input it (eg. pain, touch, proprioception)
What specifies where neurons will be born in the layers of the spinal cord?
A 2-dimensional grid made from the A-P and the D-V axis
What do TFs specify?
Neural cell types which emerge at particular positions and developmental stages - by regulating transcription of other genes in these cells
What defines a specific neuronal subtype?
TF combinations expressed by the cell
What is the evidence that BMPs and Wnts are involved in D-V patterning?
Loss of GDF7 leads to the loss of D1A neurons, but NOT D1B neurons
What happens if Wnt signalling is enhanced?
Dorsal gene expression domain expanded ventrally
What happens if Wnt signalling is reduced?
Ventral gene expression domain is expanded dorsally
What does changing Wnt expression interfere with?
Patterning/fate but NOT differentiation (neurons are still produced - BMP antagonists)
What happens to neural identity over time?
It changes
What helps to set up interneuron domain BOUNDARIES?
CROSS-REPRESSION between transcription factors:
- TF promote gene expression in their target and repress TF which would have defined a neighbouring region
- Forms ‘striped domains’
What does TF cross-antagonism refine?
The pattern laid down by BMP/Wnt/Shh signalling
How are neuronal subtypes different to each other?
- Express different neurotransmitters
- Different migratory pathways
- Different receptors
- Different axonal projections
- Different circuit integration
