Module IV - Lecture 0 - LTD Notes

Question 1

What is the activity dependent weakening of synapses?

Answer 1

LTD long term depression

Question 2

If you take a CA1 pyramidal neuron and cause it to fire by stimulation at 1Hz/1s for about 15mins then what occurs?

Answer 2

an AP will be generated in the presynaptic neuron but only sometime will a postsynaptic neuron generate an AP - so there will be asynchronous firing so this will tell the postsynaptic neuron and the presynaptic neuron that we are not firing or processing identical information as the presynaptic neuron so then look at the AMPA currents in the postsynaptic neuron they are smaller so the AMPA receptor has been taken away from the synapse

Question 3

What is needed for LTD?

Answer 3

NMDA receptor activation

Question 4

What happens if neurons do not fire at the same time and are offset in terms of firing?

Answer 4

the synapses shrink and they get weaker so neurons dealing with nonassociated information and they will not be connected as much

Question 5

What is an NMDA receptor antagonist and prevents glutamate from binding to NMDA receptors?

Answer 5

APV

Question 6

What happens to LTD if you block NMDA receptors with APV?

Answer 6

you end up blocking LTD

Question 7

What causes glutamatergic synapses to shrink and have fewer AMPA receptors?

Answer 7

LTD

Question 8

If you do a glutamate uncaging experiment where you uncage glutamate at a spine at a constant low frequency what happens to the AMPA current and why?

Answer 8

the AMPA current goes down because the size of the synapses goes down and the smaller the spine the less AMPA receptors

Question 9

Does LTD require ion flow through the pore of the NMDA receptor?

Answer 9

no it does because an experiment in which 7CK which blocks the pore of the NMDA receptor found that LTD is not gone this means that LTD might be rather dependent on the metabotropic function of the NMDAr in which it can interact with other proteins downstream and cause LTD