Synapses and Plasticity Three

Question 1

What is long term potentiation?

Answer 1

The increase of synpatic strength (current going through post synpatic receptors)

Question 2

How is LTP achived?

Answer 2

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

Question 3

What does EPSC stand for?

Answer 3

Excitatory Post Synaptic Current

Question 4

What does EPSP stand for?

Answer 4

Excitatory Post Synaptic Potential

Question 5

When measuring synaptic strength without any stimulation, what is recorded?

Answer 5

The baseline level of synaptic strength(current flow)

Question 6

What are the three phases of LTP?

Answer 6

Induction
Expression
Maintainence

Question 7

What is induction in regards to LTP?

Answer 7

Stimulation that induces LTP

Question 8

Can LTP occur without induction?

Answer 8

No

Question 9

What is expression with regards to LTP?

Answer 9

How synaptic strength is actually increased.

Question 10

What is maintenance with regards to LTP?

Answer 10

How the increased strength is maintained

Question 11

Can short term potentiation occur?

Answer 11

yes but we dont need to know this

Question 12

Can LTP occur indefintely?

Answer 12

Stimulation up to a certain strength can occur, beyond this further stimulation will not allow an increase in synpatic strength (saturation)

Question 13

What are three properties of LTP?

Answer 13

Input specificity
Saturable
Associativity

Question 14

What does input specificity mean with regards to LTP?

Answer 14

Input specificty means that only the synapses that are stimulated get potentiated

Question 15

What does saturable mean with regards to LTP?

Answer 15

Synapses that are stimulated increase to the maximum level

Question 16

What does associativity mean with regards to LTP?

Answer 16

(co-operativity) LTP requires both post synaptic simtulation and presynaptic neurotransmitter release

Question 17

What are three methods of inducing LTP?

Answer 17

Tetanic Stimulation
Pairing
Theta burst stimulation

Question 18

What is tetanic simulation?

Answer 18

Breast bursts of high frequency stimulation of axons (100hz) resulting in high levels of neurotransmitter release and AMPA activation- depolarisation

Question 19

What is pairing?

Answer 19

Presynaptic stimulation at 1hz paired with post synaptic depolarization achieved by current injection.

Question 20

What is theta burst stimulation?

Answer 20

Hippocampus has natural theta rhythm (6-10hz) theta rhythm oscillations.

Question 21

what does camkII stand for?

Answer 21

Calcium calmodulin dependent kinase II

Question 22

What does LTP require in terms of synapse?

Answer 22

Glutamate release and activation of NMDA

Question 23

If a patient was given NMDA receptor blocker could LTP be achieved?

Answer 23

No

Question 24

Why is camKII unique?

Answer 24

High levels of camkII in neurons and no where else in the body (makes up 2% of protein in neurons)

Question 25

What does camkII do?

Answer 25

Phosphorylates AMPA which causes their insertion into the membrane and increased currecnt conduction through AMPA receptors

Question 26

What does increased AMPA receptors do?

Answer 26

Increases the Na flux upon glutamate activation and thus increased depolarisation

Question 27

Describe the LTP process entirely:

Answer 27

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)