Homeostatic Plasticity Flashcards
synaptic pruning
eliminates weak or unused synapses to maintain balanced firing rates within a network
increases efficiency and makes stronger connections
LTP
strengthens synapses
post synaptic neurons become more responsive to presynaptic neurons
what is runaway excitation
hyperefficient synapses
positive feedback loop (postsynaptic neurons fire more readily which triggers LTP in neighbouring synapses)
risk of seizures
TTX and wash
blocks NaV and APs - blocks excitation
wash - hyperexcitability
bicuculline and wash
blocks GABAa R - causes hyperexcitation
wash - little innervation
monocular eyelid suture vs ablation of both retina
monocular lid suture - decreases firing
ablation - decreased then increased firing
set point
varies for each neuron (cell-autonomous)
synaptic scaling
neurons adjust the strength of synapses in response to chronic changes in neural activity - maintain a stable firing rate
uses multiplicative change (strength is increased/decreased by the same factor)
intrinsic plasticity
modifies the response curve of a neuron
rightward shift - decreased excitability raises threshold
leftward shift - increased excitability lowers threshold
plasticity types
- STDP (spike time dependent plasticity) faster ms - strengthens synapses in learning
- synaptic HP - increases synaptic strength of a neuronal network after sensory deprivation
- intrinsic HP - lowers threshold
how are AMPAr held in place
scaffolding proteins
NBQX
AMPA R antagonist
interferes with glutamate signalling - replenishes pool of vesicles
TTX vs Gabazine
TTX (inactivity) more Ca2+ influx - bigger AP response
Gabazine (high activity) - weaker response
TNF-a
tumour necrosis factor alpha
increased AMPA R expression, decreased GABA R expression
in tnf-/- glia - exposure to TTX induces no homeostatic plasticity
Kir 2.1 neuron
Kir spike rate initially low then increases at Day 14
