Nervous System 4 - Experiments and Mechanisms

Question 1

What is Synaptic Transmission modified by?

Answer 1

By past activity and by behavioural experiments

Question 2

What is Synaptic Plasticity?

Answer 2

The capacity to alter the physiological strength of a transmission

Question 3

What are the two forms of Synaptic Plasticity?

Answer 3

Short term and Long term

Question 4

What are Short term and Long term plasticity distinguished by?

Answer 4

Their durations (from seconds to hours and days) and by the underlying molecular mechanisms

Question 5

What does Short Term Plasticity entail?

Answer 5

Local changes of the synapse

Question 6

What does Long Term Plasticity ential?

Answer 6

Changes in protein synthesis and gene transcription

Question 7

What is a good measure of Synaptic Strength?

Answer 7

Amplitude of EPSP

Question 8

What is a good measure of Synaptic Plasticty?

Answer 8

Changes in EPSP amplitude

Question 9

What is Long Term Potentiation (LTP)?

Answer 9

A form of synaptic plasticity that involves strengthening of the synapses

Question 10

What do many of the synapses in the hippocampus show?

Answer 10

Long Term Potentiation

Question 11

What is Consolodation?

Answer 11

When short term memory gets converted into long term memory

Question 12

What is the most intensively studies pathway in neuro research?

Answer 12

The Schaffer Collateral

Question 13

What is Tetanus?

Answer 13

Intense stimulation at a high frequency

Question 14

What does Tetanus cause?

Answer 14

It cause the EPSP to increase causing synaptic strength to be boosted

Question 15

Why can LTP only be seen in the pathway that was stimulated?

Answer 15

Because LTP is pathway specific

Question 16

Why is it important that LTP is pathway specific?

Answer 16

Because if it wasn’t LTP would saturate all the circuits and not allow for anymore plasticity

Question 17

How long can LTP last for?

Answer 17

For several hours in a sliced hippocampus and for more than a year in intact animals

Question 18

What is the Primary Excitatory neurotransmitter?

Answer 18

Glutamate (Glu)

Question 19

Which receptors does Glutamate (Glu) bind to?

Answer 19

NMDA and AMPA receptors

Question 20

What are NMDA and AMPA receptors named for?

Answer 20

Synthetic chemicals that were designed to identify these receptors

Question 21

What happens when glutamate reaches a postsynaptic neuron at rest?

Answer 21

It binds with AMPA and NMDA receptors. The AMPA receptor allows sodium to enter while the NMDA receptor is blocked by Mg+

Question 22

What happens once Glu binds to AMPA and NMDA receptors in the postsynaptic neuron?

Answer 22

AMPA allows sodium to enter the cell while NMDA is block by Mg2+

Question 23

What is needed to unblock NMDA receptors?

Answer 23

The postsynaptic membrane has to be strongly depolarized and glutamate must be bound to it

Question 24

Why are NMDARs specialized?

Answer 24

Because they are both voltage dependant and chemically activated

Question 25

What happens to NMDARs once the membrane is strongly depolarized and glutamate is bound?

Answer 25

The Mg is expelled from the channel and Calcium and Sodium ions are able to depolarize the cell

Question 26

Why are NMDARs coincidence detectors?

Answer 26

Because they require to events to occur simultaneously in order to be activated

Question 27

Which proteins does a Silent synapse have?

Answer 27

NMDARs

Question 28

What proteins does a Functional synapse have?

Answer 28

AMPARs and NMDARs that develop through maturation of the brain

Question 29

What shows evidence of Silent synapses?

Answer 29

When the cell is clamped at -65mV (rest) no postsynaptic current occurs because the synapse only contains NMDARs which cannot conduct because Mg blocks the channel. But at +55mV (depolarization) the Mg block is removed and now current occurs

Question 30

What causes AMPARs to be inserted into a previously silent synapse?

Answer 30

LTP

Question 31

When AMPARs are activated what does it allow into the cell?

Answer 31

Sodium and Calcium

Question 32

After Calcium enter the cell through AMPARs where does it go?

Answer 32

It goes to activate CaMKII

Question 33

What does CaMKII stand for?

Answer 33

Calcium/Calmodulin protein Kinase II

Question 34

What does CaMKII do?

Answer 34

It phosphorylates proteins like AMPARs

Question 35

Why is the Phosphorylation of AMPARs important?

Answer 35

Phosphorylation of AMPARs is key for maintain LTP

Question 36

What would happen if CaMKII is blocked?

Answer 36

LTP initiation cannot occur

Question 37

How does CaMKII work in the cell?

Answer 37

Once calcium enters the cell through NMDARs it becomes activated and phosphorylates AMPARs and brings them to the cell membrane which allows for easier depolarization because they are only depolarized by glutamate

Question 38

What does adding AMPARs do?

Answer 38

Increases postsynaptic strength

Question 39

How does protein synthesis affect LTP?

Answer 39

Protein synthesis is required for maintenance of LTP

Question 40

How is protein synthesis initiated in order to produce AMPARs?

Answer 40

Protein kinases initiate cAMP which initiate Protein Kinase A which initiate CREB which is a transcription factor that allows for new synapses to grow

Question 41

What is Long Term Depression (LTD)?

Answer 41

Weakening of synaptic strength (smaller EPSPs)

Question 42

What can induce LTD?

Answer 42

Low frequency stimulation

Question 43

How does Low frequency stimulation induce LTD?

Answer 43

They involve the activation of phosphates which dephosphorylate proteins and remove AMPARs from the membrane

Question 44

What will factors that activate protein kinases or inactivate phosphates do?

Answer 44

Promote LTP and reduce LTD

Question 45

What will factors that activate phosphates or inactivate kinases do?

Answer 45

Promote LTD and reduce LTP