lecture 14 - synapse stabilisation and neuronal maturation Flashcards
are synapses lost or gained during development
lost
what is polyinnervation
where each muscle fibre receives multiple inputs and each motor neuron innervates multiple fibres
what is monoinnervation
each fibre receives input from a single motor neuron
at which stage of development are muscle fibres polyinnervated
initial
why is there initially dis-coordiation of synapses
due to only 1 of 3 synapses firing at any one time
what does deliberate non-coordinated firing increase the rate of
synaptic loss
describe the ‘reward’ pathway for neurotrophins
high MMP
high BDNF
triggers synaptic potentiation through TRkb
describe the ‘punishment’ pathway for neurotrophins
low MMP
more proBDNF
axonal retraction due to signals via p75-NTR
what does blockage of TrkB accelerate
synapse elimination
what do experiments in eyes of animals tell us about synapse stabilisation
that inputs compete for synaptic partners based on activity
why is the NMDA receptor called a coincidence receptor
it is activated in response to pre synaptic glutamate release and post synaptic action potentials at the same time
what determines neuronal maturation
transcription factors determine which genes are expressed so which set of neurotransmitters are made
how do the triceps and latissimus dorsi develop different neuronal connections in the CNS
tricep develops monosynpatic connections due to no GDNF expression
latissimus dorsi develop polysynaptic connections dues to expression of GDNF
what type of target development do mechanosensors have
inter-dependant
what are the three types of target development
dependant on inputs
independant
inter-dependant (rely on eachother)
what 2 things is neuronal phenotype a combination of
initial patterning factors that dictate TFs
targets and signals encountered as the circuit forms
what did Viktor Hambuger discover about synapse stabilisation
that synapses aswell as cells are lost during development
what happens when you block TTX
no competition
no synapse loss
what does loss of p75-NTR lead to
prevention of synapse elimiation
what does addition of BDNF in vivo do
suppress synapse elimination
what does blockage of TrkB do
accelerates synapse elimination
describe the ocular dominance column experiement
inject radioactive aas into eye of adult
reveals specific layers /columns in the visual cortex
columns only appear 3 weeks after birth which support the ‘use it or lose it’ theory
the columns reflect which input is dominant
what does pro BDNF induce
LTD
what is GDNF
glial derived neurotrophic factor
