Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro 3660 > Chapt. 2 - LTP > Flashcards

Chapt. 2 - LTP Flashcards

1
Q

A common, but now incorrect, view of memories and the brain is

A

that the brain was thought to be a warehouse, that memories could be stored away as items in the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the correct idea of how memories are acquired in the brain

A

the brain records/ represents experiences and certain ensembles of neurons are activated to acquire the memory. the neurons are later reactivated to retrieve that memory again

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cell assemblies

A

Donald Hebb proposed that they are modified ensembles of neurons and are the substrate (where they live) for memories.
It describes the network of neurons that are repeatedly being activated and therefore strengthening their connection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why do neurobiologists believe that information about experiences can persist in a retrievable form

A

because the synapses (point of contact between neurons) can be modified by experience (strengthened/affecting probability of reactivating)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Explain plasticity as a mechanism

A

plasticity is not believed to be apart of memory itself, but a more general phenomenon of the nervous system. It is only a mechanism for acquiring and helping other structures to store that memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Konorski and Hebb proposed what idea about plasticity

A

that the synapse was the critical site of plastic change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What rule did Hebb propose to specify how synaptic connections can be modified

A

with repeated firing between the same cells, some growth process or metabolic changes takes place in both cells and they become more efficient and stronger together.
cells that fire together, wire together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Memories from the brain’s view are…

A

the changes in the connectivity in the collection of neurons responding to an experience. the changes are not localized and are distributed among neural systems that are involved in memory producing processes/events

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Connections between neurons are changed when…

A

the synapse that link them are modified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is it a challenging task to want to understand how modifications between synapses occur

A

requires locating neurons in the engram and their natural sensory inputs

simplified this task through the discovery of long-term potentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define long term potentiation (LTP)

A

the persistent strengthening of synapses based on recent pattern activity. These patterns produce a long-lasting increase in signal transmission between neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What structure was mainly used while studying LTP and why

A

the hippocampus because of the well understand anatomy of the hippocampus. it makes it possibly to study connections between neurons in or region or subfield with neurons in another.
strategy (through the understanding of the trisynaptic circuit) = stimulate set of fibers known to synapse onto neurons in a particular subfield and record hat happens in that region when the impulse arrives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Trisynaptic circuit components

A

neurons in entorhinal cortex connect to dentate gyrus (region of hippocampus) through the perforant path
then neurons in dentate gyrus connect to CA3 pyramidal cells through mossy fibers
then neurons in CA3 connect to neurons in CA1 pyramidal cells through Schaffer collateral fibers
(this circuit of particular interest because allowed study of neurons between subfields)
these connections also had clear large fibre tracts
knew the order of the circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Experiment about question “is it possible to artificially modify the strength of synapses?”

A

Bliss and Lomo stimulated fibers in perforant path (neurons from entorhinal to dentate) recorded the synaptic activity in the dentate gyrus and found LTP.
applied weak stimulus and measured synaptic activity and same for strong stimulus.
then repeatedly presented the weak stimulus and found that it evoked a bigger response and this enhanced response is called LTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

LTP last for how long

A

at least several hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

LTP is an important discovery because it provided a way to study what

A

how synaptic strength can be modified by experience

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In vitro preparation

A

dissect thin slice of tissue from hippocampus and placing it into chamber with chemicals in a solution to keep it alive for a few hours. then a stimulating electrode is positioned to deliver electrical current to a chosen set of fibers (usually schaffer collateral fibers and record CA1 response). the electrode measures
the (excitatory postsynaptic potential) EPSP, in the extracellular space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define EPSP

A

excitatory postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential (high EPSP more likely to fire? therefore more LTP?)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the dependent variable when studying long term potentiation

A

fEPSP (field excitatory postsynaptic potential)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is EPSP used to display/measure LTP

A

high frequency of stimuli so the same axons causes LTP which is shown by a long lasting increase in EPSP amplitude

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

A neuron is a ______, ____, ____, and _____ device

A

input device - receives chemical and electrical messages from other neurons
integrative device - combines messaged received from multiple inputs
conductive output device - sends info to other neurons, muscles, and organs
representation device - stores information about past experiences as changes in synaptic strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

A synapse is composed of

A

a presynaptic terminal (axon bouton) and a postsynaptic component separated by the synaptic cleft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does the postsynaptic potential do in the postsynaptic current

A

it is excitatory or inhibitory potential that changes the excitability of the postsynaptic cell, caused by changes in membrane potential

24
Q

what causes negative membrane potential

A

caused by different concentrations of positive and negative ions, different sizes of ion channels or permeability of the membrane, pumps, etc.
DUE TO CHANGES IN CONCENTRATION

25
Q

membrane potential is ____ and can be driven either less or more _____

A

dynamic
negative

26
Q

depolarization represents the case when the membrane potential becomes _____ and drives the neuron ____ generating action potentials

A

less negative (closer to zero)
towards

27
Q

hyperpolarization represents the case when the membrane potential becomes _____ and drives the neuron ____ from generating action potentials

A

more negative
away

28
Q

What is used to generate action potentials to produce LTP in the hippocampus?

A

electrical stimulation

29
Q

Post synaptic depolarization

A

(ex. after electrical stimulation used to produce LTP to generate action potentials) resulting in synapses on the post synaptic neurons to depolarize. positive ions will flow into the neurons

30
Q

Field EPSP

A

measure of the strength of a population of synapses and reflects the depolarization of many synapses.

31
Q

What is the strength of synapses defined by

A

the change in transmembrane potential resulting from activation of the postsynaptic neurotransmitter receptors

32
Q

What are the two ways to record postsynaptic potentials

A

intracellular electrode - penetrates neuron that detects positive ions flowing into the neuron to indicate depolarization.
electrode placed into extracellular fluid - measures electrical potential between extracellular fluid and a ground electrode

33
Q

What is measured of the fEPSP to measure the strength of the synaptic connections

A

the slope of the fEPSP indirectly measures strength because fEPSP is the rate that positive ions flow away from the extracellular recording electrode and therefore the positive ions are entering the postsynaptic neuron and depolarizing.

34
Q

Synaptic strength is measured by how much

A

postsynaptic depolarization is produced by the stimulus.

35
Q

Increase is fEPSP represents and _____ in synaptic strength

A

increase

36
Q

What are the waveform components from a recording electrode

A
  1. stimulus artifact - stimulus used to evoke action potential/triggering the current generator/electrode
  2. fiber volley - the action potentials generated by the electrical stimulus
  3. fEPSP - downward slope of the waveform, this is the positive Na leaving, meaning they are depolarizing
37
Q

How is fEPSP calculated

A

represented as a % baseline.
difference between fEPSP produced by test stimulus during baseline period prior to inducing stimulus (T1) and response to test stimulus after inducing (T2)
T2/T1 x 100 = %

38
Q

When testing using LTP methodology, the test stimulus serves what two functions

A
  1. establishes a baseline 2. used to determine if the inducing stimulus produced LTP
39
Q

What is LTD (long term depression)

A

case in which synaptic activity weakens the strength of synaptic connections. delivery a low frequency stimulus for long period of time

40
Q

Why was the phenomenon of LTP so interesting to learning and memory researchers

A
  1. cooperativity - requires cooperative interaction of afferent fibers in a system
  2. specificity - restricted to synapses activated (not all synapses that contact the same neuron)
  3. associativity - synapse which cannot produce LTP with weak input can undergo LTP when the synapse is coactivated via a strong input
41
Q

What is done in order to produce LTP

A

experimenter applies electrical stimulation to axon fibers to cause release of nts to a populations of synapses on postsynaptic neurons

42
Q

What does LTP represent

A

the strengthening of synapses activated by inducing the stimulus (increase in capacity of these synapses to influx positive ions in response to the test stimulus)

43
Q

Define signaling cascade

A

a series of chemical reactions which occurs as a result of a single trigger reaction involved in synaptic modificiation

44
Q

Define signaling cascade

A

a series of chemical reactions which occurs as a result of a single trigger reaction involved in synaptic modification

45
Q

A signaling cascade is initiated by what

A

the first messenger - an extracellular substance (hormones or nts) that bind to a cell-surface receptor and initiates intracellular activity

46
Q

What is the second step in a cascade

A

second messengers - relay signals from receptors on the cell surface to target intracellular proteins

47
Q

What is the order of signaling cascades

A

first messenger –> second messenger –> proteins –> into both kinases and phophatases –> structural and functional proteins

48
Q

Why are second messengers so fast and what does that allow for

A

synthesis of them do not depend on slower transcription and translation processes.
this allows for rapid production of second messengers which provide a way to amplify the effects of the first messengers inside the cell

49
Q

Define kinases

A

proteins that can change the function of other proteins.
composed of inhibitory and catalytic unit
can be active or inactive state

50
Q

What happens after a second messenger binds to the kinase

A

inhibitory unit is dissociated and kinase is in active state
in active state, catalytic unit can phosphorylate other proteins (add phosphate group) and change their function

51
Q

Define phosphatases

A

proteins that remove phosphate groups

52
Q

What is happening in the normal state of kinases

A

normally in its inactive state and the catalytic unit cannot phosphorylate other proteins

53
Q

What are the three principles of LTP

A
  1. duration of LTP can vary
  2. duration of LTP depends on the set of molecular processes engaged by synaptic activity
  3. synapses are strengthened and maintained in a sequence of temporal, distinct but overlapping processes
54
Q

What are TBS (theta burst stimulation)

A

high volume stimuli for short period. the number of TBS determines the duration of LTP
implies that synaptic strength can vary in duration and may have different molecular bases
(depends on TBS intensity which makes duration different)

55
Q

What three general sets of molecular processes contribute to the durability of LTP

A
  1. post translation processes (assemble and rearrange existing proteins)
  2. transcription
  3. translation processes - generate new proteins
56
Q

Sequence of molecular processes contribute to duration of LTP

A

high frequency stimulation –> synaptic activity –> biochemical interactions –> into both assemble: post translation modifications and generate: transcription and translation –> enhanced AMPA receptor function –> strengthened synapses –> LTP

57
Q

Changes in synaptic strength that support LTP evolve in overlapping stages by unique molecular processes. what are these stages

A
  1. generation 2. stabilization 3. consolidation 4. maintenance

Neuro 3660 (27 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions