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Neural Basis of learning and memory > LTP > Flashcards

LTP Flashcards

1
Q

What is an Engram?

A

the physiological representation of learning and memory

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2
Q

What is consolidation?

A

The process of producing the physiological change/ The formation of the engram

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3
Q

What is synaptic facilitation

A

it is the “strengthening” of the synapse between the pre-synaptic neuron and the post-synaptic neuron

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4
Q

What is Donald Hebb’s theory for the formation of an engram

A

Repeated excitation of particular synapse: often/fast enough stimulation to strengthen

Simultaneous firing of 2 neurons

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5
Q

What does “strengthened” synapses mean?

A

it means when the pre-synaptic neuron released NT that the post-synaptic neuron is more likely to fire an action potential next time it is stimulated by that specific neuron

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6
Q

What is co-occurence?

A

if cells are active at the same time often enough, long-term changes in the synapse facilitate subsequent transmission

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7
Q

Explain what Stronger means in reference to the synapse

A

It means that when the particular pre-synaptic neuron activates the post-synaptic neuron it is more likely to reach the threshold to create an action potential in relation to a normal non-strengthened neuron activating the same post-synaptic neuron

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8
Q

Using Pavlov’s experiment with his dogs. Explain a simple model of how a UCS(food) and a CS(bell) interact to create a UCR(salivation) that can be used to explain Hebbian Synapses

A

the CS(bell) is on neuron(pre-s) and the UCS(food) is the other neuron(pre-s) both of these neurons have synapses on the UCR(salivation) neuron(post-s). When the dog has shown the food, the UCS neuron fires and activates the UCR neuron making the dog salivate. When the UCS neuron is paired with the CS neuron, both fire simultaneously and activate the UCR neuron. As this happens repeatedly, the synapse between the CS and the UCR neuron is strengthened when “naturally” it wouldn’t be. After the dog has been conditioned when the CS fires alone and is not paired with the activation of the UCS the dog’s UCR neuron is triggered and the dog salivates.

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9
Q

What are ways of synaptic facilitation?

A

Increase the number of receptors

Increase the number of synapses

Increase the NT release from pre-s

Change the sensitivity of the post-s membrane

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10
Q

What is EPSP?

A

Excitatory post-synaptic potential: the potential of the neuron to reach the threshold and fire and action potential

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11
Q

What is a tetanized input?

A

It is an input that happens very rapidly and is artificial and does not occur physiologically

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12
Q

What are the three main structures of the Hippocampus?

A

Dentate Gyrus, CA3, and CA1

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13
Q

Where does the Entorhinal cortex go to?

A

Synapse on the Dentate Gyrus via the perforant pathway

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14
Q

Where does the Dentate gyrus granule cells synpase?

A

CA3 pyramidal cells via the mossy fibers

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15
Q

Where does CA3 synapse?

A

CA1 via the schaffer fibers

Contralateral CA3 and CA1 via commissural fibers

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16
Q

What happens if you stimulate the mossy fibers?

A

the CA3 pyramidal cells will be activated

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17
Q

What happens if you stimulate the Schaffer collaterals?

A

You will activate the CA1 as well as the contralateral CA3 & CA1

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18
Q

What do Hebbian, Homosynpatic, and Associative induced LTP to have in common?

A

Stimulation of afferent neurons

all induce LTP

All in essence do Hebbian: they all depolarize the cell enough that when it is activated again it has a larger effect on EPSP

19
Q

What is the cooperative characteristic of LTP?

A

With HFS(high frequency stimulation), need a certain minimum number of presynaptic fibers activated

20
Q

What is the input-specific characteristic of LTP?

A

LTP changes excitability at particular synapses, not the whole neuron

21
Q

What is the associative characteristic of LTP?

A

LTP can result from the concurrent activation of converging inputs

22
Q

What is homosynaptic induced LTP?

A

Repeated, rapid stimulation of 1 set of afferents (tetanic stimulation)

23
Q

What is Associative Induced LTP?

A

Simultaneous. stimulation of 2 sets of afferents

24
Q

Cooperative characteristic of LTP

A

with HFS, need certain minimum number of presynaptic fibers activated

25
Q

Input-Specific Characteristic of LTP

A

LTP changes excitability at particular synapses, not the whole cell

26
Q

Associative characteristic of LTP

A

LTP can result from concurrent activation of converging inputs

27
Q

What is early phase LTP?

A

1 stimulus, no protein synthesis required

28
Q

What is late phase LTP?

A

4 stimulus trains over a period of time(repetition is important), and protein synthesis required(changing the morphlogy)

29
Q

what is In vitro?

A

Neurons grown in a class dish

30
Q

What is ex vivo?

A

Neurons taken from a brain and experimented on in a glass dish(hippocampal slice)

31
Q

what mechanism of LTP is NMDA dependant?

A

Associative LTP in CA1

32
Q

What is metabotropic?

A

Not direct it is a 2nd messenger system

33
Q

What is the major characteristic of NMDA?

A

Voltage and ligand gated

34
Q

What does it mean to be voltage and ligand gated receptor?

A

The response to GLUT depends on post synaptic membrane potential

Not depolarized: Mg2+ blockade prevents Ca2+ influx

Depolarized: Mg2+ blockage is removed, glut binding produces Ca2+ influx

35
Q

Characteristic of AMPA receptor?

A

Ligand gated

GLUT binds -> Channel Opens -> Na+ influx -> depolarization

36
Q

What is Non-Coincident stimulation?

A

AMPA receptor activated, NMDA not

37
Q

what happens when LTP is induced?

A

Repeated/Simultaneous stimulation of AMPA -> depolarization -> Mg2+ block is removed -> Ca2+ influx thru NMDA

38
Q

What do retrograde messengers do?

A

They give feedback from post to pre-synaptic changes: protein kinases

39
Q

What is the mechanism of maintenance of pre-synaptic mechanism?

A

Ca2+ -> Calmodulin Activation -> activation of various kinases -> release of retrograde messengers -> activation of pre-syn protein kinases -> increased GLUT release

40
Q

What is the mechanism for post-syn LTP mechanisms?

A

Ca2+ influx -> Ca2+/Calmodulin kinase activation -> Exocytosis of AMPA -> phosphorylation of AMPA receptors -> increased excitability

41
Q

What is a filopodia?

A

an immature dendritic spine

42
Q

How do filopodia turn into mature dendritic spines?

A

The filopodia forms postsynaptic density from ambient glutamate, It then releases retrograde signaling that then creates and active zone on the axon of a nearby cell. This active zone then releases NTs that active the postsynaptic membrane. Which then releases retrograde signaling and the synapse is strengthened

43
Q

What are the changes in morphology of existing spines in late-phase LTP.

A

Few mins after LTP: increased receptors and glut release
30mins after: spine head enlarges: synaptic strengthening
Big synapses break apart and form a double-headed spine and then those split and form two spines

44
Q

What criteria does LTP meet to be a mechanism for learning?

A

Detectability: learning induces LTP
Mimicry: LTP induces learning
Anterograde Alteration: block LTP, block Learning; induce LTP, induce learning
Retroade Alteration: erase LTP, erase memory

Neural Basis of learning and memory (10 decks)

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