Synaptic Plasticity and Memory Flashcards
What are the 3 forms of synaptic plasticity?
LTP
LTD
Depotentiation
What is depotentiation?
Initial LTP followed by LFS which brings the level of potentiation back to baseline
What is the main mechanism for maintaining LTP?
Changes in trafficking of AMPARs
Outline AMPAR receptor trafficking in LTP
NMDAR lets Ca2+ in
This activates CaM > CaMKII
CaMKII causes AMPAR phosphorylation so they can function on the membrane and allow current through
What is Hebb’s postulate
When the axon of cell A is near enough to excite cell B
And repeatedly does so
There is a growth/metabolic change in firing
So that the efficacy of B firing is stronger
Which neural circuits may synaptic plasticity be implemented in?
Reflex networks
Distributed associated network
Which criteria can be used to assess the synaptic plasticity and memory hypothesis?
Anterograde alteration
Retrogradation alteration
Detectability
Mimicry
Martin et al 2000
What is the anterograde alteration criteria?
If you block synaptic changes at the time of learning it should prevent learning/memory formation
What is the retrograde alteration criteria?
If you wipe out the learning induced synaptic changes, it should get rid of the memory
What is the detectability criteria for synaptic plasticity and memory?
Detectable changes should occur in the expected brain region
What is the mimicry criteria for synaptic plasticity and memory?
Should be able to create a memory of something that didn’t happen by altering the relevant part of the brain
How can you assess the anterograde alteration capacity of memory?
Blocking of NMDAR (with DL-AP5) receptors prevents LTP
Impairs MWM performance (bc doesn’t remember!)
How did Base et al 2005 demonstrate that synaptic plasticity learning is subject to anterograde alteration?
One-trial place memory task
Food in sandwells
With NMDAR antag BEFORE first exposure to food cant find again
NMDAR antag AFTER first exposure can find
ie NMDAR needed for memory formation but not retrieval
Which receptors are needed for memory retrieval?
AMPAR
Base et al 2005
Which kind of AMPAR receptors are needed for LTP and where?
GluA2-lacking AMPARS
CA1
Zhou et al 2018
How do we know that GluA2-lacking AMPARs are needed for CA1 LTP?
GluA2 tails on gluA1 neurons stops em workin
Don’t have any increased searching and the Sandwell with food in compared to other sandwells
Which receptors are required for full memory retrieval with partial information?
NMDAR at CA3
Nakazawa et al 2002
What is ZIP?
Inhibitor of PKMzeta
What is the effect of ZIP on LTP?
Reverse it (depotentiation)
Pastalkova et al 2006
How do pastalkova et al demonstrate that ZIP erases spatial memory?
Shock animal in certain location until it learn to avoid it
Then given ZIP, essentially “unlearns” and goes back to sector
Pastalkova et al 2006
What are the problems with detectability?
Where should you look in the brain? Many many neurons
How big a change are we looking for?
Is it saturable?
Which type of learning is the amygdala associated with?
Fear learning
Associative conditioning
In which ways is fear learning similar to LTP?
Traffics AMPARs to the post synaptic membrane
Which type of neural network is evident in the hippocampus?
Distributed associative network
Why is the morris water maze a good test for hippocampal synaptic plasticity?
Hippocampal NMDAR function and LTP needed to create spatial memory
What is a distributive network?
One where CA1 neurons synapse on CA3
And then send signals back to their own dendritic fields and fields of neighbours
What does a distributive complex allow for?
Retrieval of a whole memory from a partial one
Why does PKMzeta inhibition cause depotentiation?
PKMzeta needed for AMPAR trafficking to membrane (to continue the phase I of LTP)
Fear condition recruits AMPARs to the membrane in a similar way to LTP
T/F
T
Rumpel et al 2005
What are the two main forms of memory?
Explicit
Implicit
Where is declarative memory stored?
Hippocampus
Medial temporal lobe
Diencephalon
Which kind of AMPARs are necessary for spatial memory formation?
GluA2 lacking
Zhou et al 2018
NMDAR dependent plasticity is needed where for full memory recovery from partial information?
CA3
Nakazawa et al 2002
