Synapses and Plasticity Three Flashcards
What is long term potentiation?
The increase of synpatic strength (current going through post synpatic receptors)
How is LTP achived?
Simulatenous high levels of activation of pre and post synaptic cleft, depolarizes the membrane (AMPA) enough to remove the Mg from NMDA allowing Ca in that activates CamKII that phosphorylates more AMPA, that is inserted into the post synpatic memrbane
What does EPSC stand for?
Excitatory Post Synaptic Current
What does EPSP stand for?
Excitatory Post Synaptic Potential
When measuring synaptic strength without any stimulation, what is recorded?
The baseline level of synaptic strength(current flow)
What are the three phases of LTP?
Induction
Expression
Maintainence
What is induction in regards to LTP?
Stimulation that induces LTP
Can LTP occur without induction?
No
What is expression with regards to LTP?
How synaptic strength is actually increased.
What is maintenance with regards to LTP?
How the increased strength is maintained
Can short term potentiation occur?
yes but we dont need to know this
Can LTP occur indefintely?
Stimulation up to a certain strength can occur, beyond this further stimulation will not allow an increase in synpatic strength (saturation)
What are three properties of LTP?
Input specificity
Saturable
Associativity
What does input specificity mean with regards to LTP?
Input specificty means that only the synapses that are stimulated get potentiated
What does saturable mean with regards to LTP?
Synapses that are stimulated increase to the maximum level
What does associativity mean with regards to LTP?
(co-operativity) LTP requires both post synaptic simtulation and presynaptic neurotransmitter release
What are three methods of inducing LTP?
Tetanic Stimulation
Pairing
Theta burst stimulation
What is tetanic simulation?
Breast bursts of high frequency stimulation of axons (100hz) resulting in high levels of neurotransmitter release and AMPA activation- depolarisation
What is pairing?
Presynaptic stimulation at 1hz paired with post synaptic depolarization achieved by current injection.
What is theta burst stimulation?
Hippocampus has natural theta rhythm (6-10hz) theta rhythm oscillations.
what does camkII stand for?
Calcium calmodulin dependent kinase II
What does LTP require in terms of synapse?
Glutamate release and activation of NMDA
If a patient was given NMDA receptor blocker could LTP be achieved?
No
Why is camKII unique?
High levels of camkII in neurons and no where else in the body (makes up 2% of protein in neurons)
What does camkII do?
Phosphorylates AMPA which causes their insertion into the membrane and increased currecnt conduction through AMPA receptors
What does increased AMPA receptors do?
Increases the Na flux upon glutamate activation and thus increased depolarisation
Describe the LTP process entirely:
Sufficienty pre and post synaptic activation results in the release of Mg from the NMDA receptor and its activation. This allows Ca influx which binds and activates camkII. CAMKII phsophorylates AMPA receptors which are then inserted into the post synaptic cleft. This means that upon gluatamte release more receptors are activate, generating large Na influx. (LTP)
