Assignment 5 Flashcards
Where in the brain are memories stored?
a) In the medial temporal lobe
b) In the striatum
c) In the strength of the synapses of the neurons that belong to the engram
d) In the hippocampus
c) In the strength of the synapses of the neurons that belong to the engram
Which stage of learning and memory is most associated with the brain being able to encode raw sensory information into short-term memory?
a) Forgetting
b) Memory consolidation
c) Memory acquisition
d) Memory retrieval
c) Memory acquisition
Which of the following is necessary to study long-term potentiation? Select all that apply.
a) A weak stimulus is needed to induce LTP
b) A strong stimulus is needed to induce LTP
c) A strong stimulus is needed to establish a baseline
d) A weak stimulus after a strong stimulus is needed in order to see if LTP occurred
e) A weak stimulus is needed to establish baseline
B, D & E
b) A strong stimulus is needed to induce LTP
d) A weak stimulus after a strong stimulus is needed in order to see if LTP occurred
e) A weak stimulus is needed to establish baseline
Which of the following is true when describing long-term potentiation (LTP)? Select all that apply.
a) LTP is a way to directly observe learning and memory
b) LTP is a form a synaptic plasticity
c) There is a greater excitatory post-synaptic potential (EPSP) in response to weak stimulation
d) The post-synaptic cell has greater hyperpolarization in response to weak stimulation
e) The post-synaptic cell has greater Na+ influx in response to weak stimulation
f) The post-synaptic cell has greater gene expression in response to weak stimulation
g) The post-synaptic cell has greater depolarization in response to weak stimulation
b) LTP is a form a synaptic plasticity
c) There is a greater excitatory post-synaptic potential (EPSP) in response to weak stimulation
e) The post-synaptic cell has greater Na+ influx in response to weak stimulation
g) The post-synaptic cell has greater depolarization in response to weak stimulation
You are a scientist in a lab performing an electrophysiology experiment. You want to measure long-term potentiation (LTP) in the hippocampus. You decide to stimulate the mossy fibers. Where in the hippocampus would you record in order to measure LTP?
a) CA1
b) Perforant pathway
c) Dentate gyrus
d) CA3
e) Entorhinal cortex
f) Schaffer collaterals
d) CA3 - The mossy fibers connect the granule cells in the dentate gyrus directly to the pyramidal neurons in CA3, making it the primary site to observe changes in synaptic strength indicative of LTP. Recording in CA3 allows for the assessment of potentiation effects directly resulting from mossy fiber stimulation.
You are a scientist in a lab performing an electrophysiology experiment. You establish a baseline by administering a weak stimulus to Neuron A and measuring the response of Neuron Z. You then administer a strong stimulus to Neuron A. Predict what you would observe in Neuron Z if you next administer a weak stimulus to a new neuron, Neuron B.
a) Neuron Z will have a decreased amount of depolarization
b) Neuron Z will have a delayed response
c) Neuron Z will have an increased amount of depolarization
d) Neuron Z will have a baseline level of depolarization
d) Neuron Z will have a baseline level of depolarization
Neuron B has not previously been conditioned through a strong stimulus to induce LTP or any form of synaptic plasticity affecting Neuron Z.
You are a scientist in a lab performing an electrophysiology experiment. After establishing a baseline, which of the following could be a way to induce long-term potentiation (LTP) in the post-synaptic neuron? Select all that apply.
a) Administer a strong, high-frequency stimulus to one presynaptic neuron
b) Administer a moderate, high-frequency stimulus to two presynaptic neurons at the same time
c) Administer a moderate, high-frequency stimulus to one presynaptic neuron spaced several seconds apart
d) Administer a GABA-A receptor antagonist prior to administering a moderate, high-frequency stimulus to the presynaptic neuron
e) Administer multiple, low-frequency stimuli to one presynaptic neuron
a) Administer a strong, high-frequency stimulus to one presynaptic neuron - typical method for inducing LTP
b) Administer a moderate, high-frequency stimulus to two presynaptic neurons at the same time - spatial summation
d) Administer a GABA-A receptor antagonist prior to administering a moderate, high-frequency stimulus to the presynaptic neuron - Blocking GABA-A receptors can decrease inhibitory neurotransmission, thereby increasing the likelihood that the subsequent high-frequency stimulation will surpass the threshold needed to induce LTP.
Predict what would happen to LTP if you block only AMPA receptors
a) Depolarization would still occur because of the NMDA receptors, so LTP would also occur
b) No depolarization would occur, so LTP would not occur
c) No depolarization would occur, but LTP would still be able to occur because of the NMDA receptors
d) Depolarization would still occur, but LTP would not be induced
e) Hyperpolarization would occur, resulting in LTP
b) No depolarization would occur, so LTP would not occur - When glutamate binds to AMPA receptors, it allows positively charged ions to flow into the neuron, causing depolarization. This depolarization is necessary to relieve the Mg2+ block from the NMDA receptors, which then allows Ca2+ to enter the neuron and trigger the intracellular processes necessary for LTP induction. Without the initial depolarization mediated by AMPA receptors, the NMDA receptors would not effectively contribute to the induction of LTP.
Predict what would happen to LTP if you block only NMDA receptors
a) Depolarization would still occur because of the NMDA receptors, so LTP would also occur
b) Depolarization would still occur, but LTP would not be induced
c) No depolarization would occur, but LTP would still be able to occur because of the NMDA receptors
d) No depolarization would occur, so LTP would not occur
e) Hyperpolarization would occur, resulting in LTP
b) Depolarization would still occur, but LTP would not be induced - Blocking NMDA receptors specifically interferes with the calcium influx necessary for the induction of LTP. AMPA receptors would still mediate the initial depolarization in response to glutamate, allowing for synaptic transmission and depolarization of the post-synaptic neuron. However, without the activation of NMDA receptors, the calcium-dependent signaling pathways critical for LTP inductio
What is required for an NMDA receptor to be fully activated? Select all that apply.
a) Depolarization of the post-synaptic neuron
b) K+ enters the post-synaptic neuron
c) The magnesium plug is removed
d) GABA is released into the synapse
e) Glutamate is released into the synapse
f) Na+ enters the post-synaptic neuron
a) Depolarization of the post-synaptic neuron - This depolarization is necessary to expel the magnesium ion that blocks the NMDA receptor channel at resting membrane potential.
c) The magnesium plug is removed - This occurs as a result of the depolarization of the post-synaptic neuron, allowing calcium and other ions to flow through the NMDA receptor.
e) Glutamate is released into the synapse - Glutamate binding to the NMDA receptor is essential for its activation, in addition to the depolarization required to remove the magnesium block.
f) Na+ enters the post-synaptic neuron - Na+ entry occurs during the activation of AMPA receptors and contributes to the depolarization of the post-synaptic neuron
Which of the following is necessary in order for long-term potentiation (LTP) to occur? Select all that apply.
a) Insertion of NMDA receptors into the post-synaptic density
b) Ca2+ influx through the NMDA receptor
c) Hyperpolarization
d) Activation of protein phosphatases
e) Depolarization
f) Insertion of AMPA receptors into the post-synaptic density
g) Activation of protein kinases
b) Ca2+ influx through the NMDA receptor - This is crucial for initiating the signaling cascades that result in LTP, as calcium acts as a second messenger in various pathways that lead to synaptic strengthening.
e) Depolarization - Necessary to relieve the Mg2+ block of the NMDA receptors, allowing Ca2+ to enter the neuron when glutamate is present.
f) Insertion of AMPA receptors into the post-synaptic density - This is a key step in LTP, as it increases the post-synaptic neuron’s responsiveness to glutamate, thus strengthening the synaptic transmission.
g) Activation of protein kinases - These enzymes, such as CaMKII, are activated by the Ca2+ influx through NMDA receptors and phosphorylate various substrates, including AMPA receptors, which can lead to their insertion into the post-synaptic membrane or increase their activity, both of which are essential for LTP.
An important aspect of long-term potentiation (LTP) is the synthesis of new proteins. What must occur in order for new protein synthesis? Select all that apply.
a) CREB1 binds to the cyclic AMP response element (CRE)
b) CREB2 is phosphorylated
c) Protein kinases are activated
d) CREB1 is phosphorylated
e) CREB2 binds to the cyclic AMP response element (CRE)
f) Protein phosphatases are activated
a) CREB1 binds to the cyclic AMP response element (CRE) - CREB1 is a transcription factor that, upon binding to CRE, can initiate the transcription of genes involved in synaptic plasticity and neuronal survival.
c) Protein kinases are activated - These enzymes are crucial for the phosphorylation of various proteins, including transcription factors like CREB1, which are necessary for their activation and the subsequent gene transcription.
d) CREB1 is phosphorylated - Phosphorylation of CREB1 is a key step in its activation, allowing it to bind to DNA at the CRE sites and promote the transcription of genes required for protein synthesis and LTP.
What contributes to long-term potentiation? Select all that apply.
a) The post-synaptic cell contains more AMPA receptors in its post-synaptic density
b) There is an increase in actin cytoskeleton within the post-synaptic cell
c) Increased protein synthesis occurs in the post-synaptic cell
d) Dendritic spine size grows
e) The post-synaptic cell becomes more permeable to Na+ ions when activated
f) There is an increase in the number of dendritic spines on the post-synaptic neuron
a) The post-synaptic cell contains more AMPA receptors in its post-synaptic density - This increases the synaptic efficacy by enhancing the post-synaptic cell’s response to glutamate.
b) There is an increase in actin cytoskeleton within the post-synaptic cell - This supports the structural changes necessary for the formation and stabilization of dendritic spines, which are crucial for synaptic plasticity.
c) Increased protein synthesis occurs in the post-synaptic cell - New protein synthesis is necessary for the consolidation phase of LTP, supporting both structural changes and the maintenance of increased synaptic strength.
d) Dendritic spine size grows - This structural change can increase the volume of the post-synaptic density, accommodating more receptors and signaling machinery, thus enhancing synaptic transmission.
e) The post-synaptic cell becomes more permeable to Na+ ions when activated - The insertion of more AMPA receptors, which are permeable to Na+ ions, into the post-synaptic density can lead to this increased permeability, facilitating depolarization.
f) There is an increase in the number of dendritic spines on the post-synaptic neuron - More dendritic spines mean more potential sites for synaptic contacts, increasing the neuron’s connectivity and synaptic input.
What contributes to long-term depression (LTD)? Select all that apply.
a) Neuronal activation
b) Low concentrations of Ca2+ influx into the post-synaptic neuron
c) Increased threshold for AMPA receptors to open
d) Activation of protein kinases
e) Internalization of AMPA receptors
f) Activation of protein phosphatases
g) High concentrations of Ca2+ influx into the post-synaptic neuron
a) Neuronal activation - if there is no neuronal activation, no changes in synaptic plasticity (LTP or LDP) will occur
b) Low concentrations of Ca2+ influx into the post-synaptic neuron - Unlike LTP, which requires a high concentration of Ca2+ for its induction, LTD can be induced by lower levels of Ca2+ influx, leading to different intracellular signaling pathways being activated.
e) Internalization of AMPA receptors - The removal of AMPA receptors from the synaptic membrane decreases the post-synaptic neuron’s responsiveness to glutamate, thus weakening the synaptic transmission.
f) Activation of protein phosphatases - These enzymes dephosphorylate various proteins, including receptors and components of the cytoskeleton, which can lead to the internalization of AMPA receptors and a decrease in synaptic strength.
What contributes to whether a synapse will undergo long-term potentiation (LTP) or long-term depression (LTD)? Select all that apply.
a) The amount of depolarization results in different concentrations of K+ influx
b) Higher concentrations of Ca2+ activate protein phosphatases while lower concentrations of Ca2+ activate protein kinases
c) Higher concentrations of Ca2+ activate protein kinases while lower concentrations of Ca2+ activate protein phosphatases
d) The amount of depolarization results in different concentrations of Ca2+ influx
c) Higher concentrations of Ca2+ activate protein kinases while lower concentrations of Ca2+ activate protein phosphatases - This is true and a key factor in determining the outcome of synaptic modifications. Higher calcium levels typically lead to the activation of kinases like CaMKII, which are crucial for LTP induction. In contrast, lower calcium levels preferentially activate phosphatases, such as calcineurin, leading to LTD.
d) The amount of depolarization results in different concentrations of Ca2+ influx - This is correct. The level of depolarization affects how much the Mg2+ block of the NMDA receptor is relieved, thus influencing the amount of Ca2+ that can enter the post-synaptic neuron. Higher depolarization levels result in more significant Ca2+ influx, favoring LTP, whereas lower levels allow for less Ca2+ influx, which can favor LTD.
