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Medsci 206 > Plasticity: LTP & LTD > Flashcards

Plasticity: LTP & LTD Flashcards

1
Q

Some patterns of synaptic activity produce a long-lasting increase in synaptic strength known as …

A

Long-term potentiation (LTP)

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2
Q

Some patterns of synaptic activity produce a long-lasting decrease in synaptic strength known as …

A

Long-term depression (LTD)

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3
Q

Long-term synaptic plasticity has been studied at excitatory/inhibitory synapses in the mammalian hippocampus/hypothalamus?

A

Excitatory, hippocampus

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4
Q

The hippocampus consists of 2 thin sheets o neurons folded onto each other, what is each sheet called

A

Denate Gyrus and Ammon’s Horn

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5
Q

CA3 and CA1 are divisions from what sheet

A

Ammon’s Horn

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6
Q

The Perforant path comes from…?

A

the Entorhinal cortex

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7
Q

The perforant path axons synapse on neurons of the _______

A

Dentate Gyrus

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8
Q

The Dentate gyrus gives rise to axons called____

A

Mossy fibres

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9
Q

The axons from the Dentate gyrus synapse on cells in _____

A

CA3

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10
Q

CA3 cells give rise to axons called____ and these synapse where?

A

Schaffer collaterals synapse in CA1

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11
Q

LTP has focused on synaptic connections between ______

A

Schaffer collaters and CA1 pyramidal cells

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12
Q

Electrical stimulation of Schaffer collaterals generates _______ postsynaptic potentials (__PSPs) in the postsynaptic CA1 cells

A

Excitatory

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13
Q

How is LTP caused?

A

High requency train of stimuli to the same axons

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14
Q

Where does LTP occur?

A

All 3 excitatory synapses in the hippocampus, cortex, amygdala, cerebellum

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15
Q

Increase/decrease in synaptic strength = LTP

What happends to the amplitude?

A

Increase in synpatic strength

Increase amplitude of AMPAr EPSC

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16
Q

What lobe is the hippocampus in?

A

Temporal lobe

17
Q

LTP requires stong activity in…

A

Both Pre and post synaptic neurons

18
Q

LTP occurs through depolarization of hyperpolarization?

A

Depolarization postsynaptically

19
Q

Coincidence detector involves

A

Co-ordinated activity of presynaptic transmitter release and depolarization of the postsynaptic neuron

20
Q

LTP is input specific, meaning?

A

LTP is restircted to activated synapses rather than to all of the synapses on a given cell.

21
Q

Another properity of LTP is Associativity, what does this mean?

A

Co-operative. If 1 path is weakly activated at the same time athat a neighbouring pathway onto the same cell is strongly activated, then both synaptic pathways undergo LTP.

22
Q

Describe the 3 phases of LTP..

A

Induction: Stimulation that induces an increase in synaptic strength (blocking this phase inhibits the other phases). Though activation of NMDA receptors

Expression: How synaptic strength is increases

Maintenance: How to maintain the increase in synaptic strength. Through insertion of AMPA receptors

23
Q

How LTP works….

A
  1. High frequency stimulation causes prolonged depolarization
  2. this expels Mg2+ from NMDA receptors
  3. Ca2+ can now enter though the NMDAr into the postsynaptic neuron.
  4. Ca2+ influx activates signal transduction cascades, including CaMKII & PKC
  5. CaMKII induces phosphorylation of AMPA receptors
  6. This causes more AMPA receptors to be inserted at the postsynaptic membrane, + Increases AMPAr conductance
  7. This Increase synapse strength = LTP
24
Q

Why does NMDA behave like a co-incidence detector?

A

The channel wil only open when Glutamate is bound to the receptor + the post-synaptic cell is depolarized to relieve the Mg2+ block

25
Q

Describe the 3 methods of how LTP is induced…

A
  • Tetanic Stimulation: breif bursts of high-frequency stimulation (100Hz), lasting 1 second, THREE times. Get high glutamate release, so opening of lots of AMPA r, so depolarizing postsynaptic cell
  • Pairing: 1 Hz presynaptic stimulation + postsynaptic depolarization by current injection
  • Theta-burst: stimulation by thythm oscillators 6-10 Hz
26
Q

What do you add during the induction phase to inhibit an increase in synaptic strength

A

AP5

27
Q

LTD occurs when the Schafer collaterals are stimulated at a ___-frequency rate of about ___Hz for short/long periods?

A

low frequency rate ot 1Hz for long periods

28
Q

What determines if you get an LTP or LTD

A

The nature of the Ca2+ signal: a small and slow rise in Ca2+ leads to depression

29
Q

LTD results from Ca2+ dependent phosphatases that……

A

cleave phosphate groups from target molecules

30
Q

What happens to AMPA receptors as a result of LTD

A

Loss of synaptic AMPA receptors, due to internalization of them into the postsynaptic cell

31
Q

How do you get LTD induction ?

A

Though LFS: low frequency stimulation

32
Q

LFS is ___-___Hz for ___-___minutes

A

0.5-1Hz for 5-10 minutes

33
Q

LTD is:

A

A decrease in synaptic strength, decrease is amplitude of AMPA receptors

Medsci 206 (6 decks)

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