Question 1

Why was AP5 applied while the neuron was held at +30 mV?

Accepted Answer

This was a control to show that the responses generated at +30 mV were from NMDARs. Depolarizing the neuron to +30 mV could have activated a different voltage dependent current and not NMDARs.

Question 2

What is the basic circuitry of the hippocampus?
A) Entorhinal cortex > ______ (area) via the ________ path
B) ________ (cell layer) to ______ (cell layer) via the ___ (pathway)
C) __________ (cell layer) to _______ (cell layer) via the ______ (pathway)

Accepted Answer

(a)Entorhinal cortex > dentate gyrus (area) via the perforant path 
(b) Granule cell (cell layer) to CA3 (cell layer) via the mossy fiber (pathway)
(c) CA3 (cell layer) to CA1 (cell layer) via the Schaffer collateral (pathway)

Question 3

Which is true for spike-timing-dependent plasticity? Select all that apply.
A) If a postsynaptic neuron repeatedly fires action potentials before a presynaptic neuron, the synapse is potentiated.
B) If a presynaptic neuron repeatedly fires action potentials before a postsynaptic neuron, the synapse is depressed.
C) If a presynaptic neuron repeatedly fires action potentials before a postsynaptic neuron, the synapse is potentiated.
D) If a presynaptic neuron fires action potentials more than 100 ms prior to the postsynaptic neuron, the synapse is depressed.
E) If a postsynaptic neuron fires action potentials more than 100 ms after the presynaptic neuron, the synapse is depressed.

Accepted Answer

If a presynaptic neuron fires an action potential within ~50 ms of an action potential in the postsynaptic neuron the synaptic efficacy will increase. If the postsynaptic neuron fires ~50 ms prior to an action potential in the presynaptic neuron the synaptic efficacy will decrease. More than 100 ms in between action potentials is too long in time to have coincident activity and the synaptic weight will remain the same.

Question 4

The amnesic patient, H.M., lost the ability to store new memories, but could still remember events and people prior to his surgery. What kind of memory did he lose? Choose all that apply.
A) Explicit memory
B) Implicit memory
C) Long-term memory
D) Short-term memory

Accepted Answer

H.M. was still able to learn ‘motor tasks’, like drawing in a mirror, and his ‘working memory’ was intact as he could hold conversations with people, but he could not form long-term memories.

Question 5

Figure Q10-7 shows data from one of the first experiments demonstrating LTP by Bliss and Lomo (1973). The arrows indicate points at which high frequency stimuli were given.  Figure
A. Figure Q10-7A below depicts an example of a field EPSP prior to high frequency stimulation. The vertical line is the stimulus artifact. What would the fEPSP look like at 1 hour and 4 hours?  Figure Q10-7A
B. What would happen to the response if Bliss and Lomo had given a low frequency stimulation of about 1 Hz at 5 hours?
Question 10-8 and 10-9 refer to (Figure Q10-8) below. Figure Q10-8 shows a synaptic matrix, which describes how changes in synaptic weight can contribute to memory storage. There are presynaptic inputs A-E and postsynaptic outputs I-IV.  Figure

Accepted Answer

The answer of Figure Q10-7 shows data from one of...

Question 6

The amnesic patient, H.M., could still learn motor tasks, like learning to draw while looking in a mirror. What kind of memory is this? Choose all that apply.
A) Explicit memory
B) Implicit memory
C) Habituation
D) Sensitization

Accepted Answer

H.M. was able to learn motor tasks, which is a form of implicit memory.

Question 7

What is synaptic plasticity?

Accepted Answer

The answer of What is synaptic plasticity?...

Question 8

Which is an example of associativity? Select all that apply.
A) Input neurons A and B fire a burst of action potentials simultaneously.
B) Output neurons I and II fire a burst of action potentials simultaneously.
C) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II fire a burst of action potentials.
D) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II are depolarized.
E) Input neuron C fires a burst of action potentials at the same time that output neuron II is active.

Accepted Answer

Associativity is the associative activity between two inputs whose synaptic inputs are spatially close to each other so that the weak synapse of one of the inputs to the postsynaptic neuron is potentiated by the simultaneous activity in a neighboring strong synapse.

Question 9

H.M. could still learn a motor task. The following is a figure showing how H.M improved in his ability to trace an image over three days. If he was able to learn the motor task, but his long-term memory of learning the motor task was impaired, what do you think his performance on day 2 would look like?  Figure Q10-3

Accepted Answer

The answer of H.M. could still learn a motor task....

Question 10

Why is CaMKII a good candidate for a molecular memory molecule?

Accepted Answer

The answer of Why is CaMKII a good candidate for...

Question 11

What is long-term potentiation?

Accepted Answer

The answer of What is long-term potentiation?...

Question 12

Figure Q10-15 illustrates the data from one of the original experiments that showed evidence for 'silent synapses'. CA3 axons were stimulated while the postsynaptic response when the CA1 neuron were voltage-clamped at -65 mV.  Figure Q10-15
A. Why were the CA1 neurons held at -65 mV?
B. What happened when the CA3 axons were stimulated before pairing, in which the presynaptic CA3 neurons were stimulated while the CA1 neurons were depolarized and what are two reasons for the result?
C. What happened when the CA3 axons were stimulated after 'pairing' and what was the interpretation of the result?
D. Summarize the idea of 'silent synapses' as a form of synaptic plasticity. Include the basic conclusions drawn from the experiments outlined in this and the previous experiment.

Accepted Answer

The answer of Figure Q10-15 illustrates the data from one...

Question 13

What are 'silent synapses'? Select all that apply
A) Synapses with no postsynaptic receptors
B) Synapses in which neurotransmitter is not released from the presynaptic neuron
C) Synapses with only NMDARs in their postsynaptic surface
D) Synapses with only AMPARs in their postsynaptic surface
E) Synapses in which AMPARs are inserted into the postsynaptic surface

Accepted Answer

Silent synapses only have NMDARs. The postsynaptic membrane must be depolarized to remove the Mg²⁺ block. If the postsynaptic membrane is depolarized then the Mg²⁺ block will be removed and voltage across the postsynaptic membrane will change when glutamate is released from the presynaptic cell.

Question 14

Why does the NMDAR provide a good molecular mechanism for coincidence detection? Select the best answer. A) It is the receptor for glutamate, the major excitatory transmitter in the brain. B) It requires depolarization to remove the Mg²⁺ block. C) It allows Ca²⁺ into the postsynaptic neuron. D) The NMDAR channel can remain open for long periods of time. E) It is expressed in the hippocampus.

Accepted Answer

The NMDAreceptor is blocked by Mg²⁺ at resting membrane potentials. It requires coincident depolarization to remove this block and the depolarization is provided by co-activation of the AMPAreceptor by a preceding input. The other answers are correct, but are not involved in coincidence detection. The entrance of Ca²⁺ is important for short- and long-term changes in synaptic activity, but not in coincidence detection.

Question 15

How is LTD generated? Choose all that apply. A) High frequency stimulation B) Low frequency stimulation C) Increase in intracellular Ca²⁺ D) Activation of CaMKII

Accepted Answer

Long-term depression is generated by low-frequency stimulation, usually around 1 Hz. CaMKII and increases in Ca²⁺ are involved in LTP.

Question 16

In an experiment that showed that CaMKII was involved in synaptic plasticity, one input was stimulated at high frequency (S1), which induced LTP. LTP was not induced from a second input that was not stimulated at high frequency (S2). Later in the same experiment, constitutively CaMKII was injected into the cell body of the postsynaptic neuron and both inputs were stimulated. Stimulation of which input resulted in LTP and why? Choose all that apply.
A) Stimulation of S1 induced LTP because those synapses were already potentiated.
B) Stimulation of S1 did not induce LTP because it was occluded by prior LTP.
C) Stimulation of S2 induced LTP because of the presence of CaMKII that was paired with S2 stimulation.
D) Stimulation of S2 did not induce LTP because it was not previously potentiated.

Accepted Answer

B) Stimulation of S1 did not induce LTP because it was occluded by prior LTP, meaning the synapses were already at a potentiated state and could not be further potentiated. C) Stimulation of S2 induced LTP because the presence of constitutively active CaMKII, when paired with stimulation, could induce LTP in synapses that were not previously potentiated.

Question 17

Below is a figure showing LTP that was induced by high frequency stimulation (indicated by the arrow) at 0 minutes (traces 1 - 3).  Figure Q10-11
A. What would happen to LTP if the NMDARs were blocked with APV? Which trace would be generated?
B. What would happen if an NMDAR with a higher ion channel conductance than normal was expressed in the postsynaptic cell? Which resulting trace would be generated?

Accepted Answer

The answer of Below is a figure showing LTP that...

Question 18

In the sentence below, circle the correct terms.
LTD and LTP represent a continuum of modifications of synaptic strength. Low-frequency stimulation results in DEPHOSPHORYLATION/PHOSPHORYLATION of AMPA/NMDA receptors, which results in ENDOCYTOSIS/EXOCYTOSIS of the receptors. This results in synaptic DEPRESSION/POTENTIATION.

Accepted Answer

The answer of In the sentence below, circle the correct...

Question 19

Which is an example of cooperativity? Select all that apply.
A) Input neurons A and B fire a burst of action potentials simultaneously.
B) Output neurons I and II fire a burst of action potentials simultaneously.
C) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II fire a burst of action potentials.
D) Input neurons A and B fire a burst of action potentials at the same time that output neurons I and II are depolarized.
E) Input neuron C fires a burst of action potentials at the same time that output neuron II is active.

Accepted Answer

As defined in Section 10.5 of the textbook, cooperativity induces LTP at a synapse when two events coincide: (1) The presynaptic cell fires and releases neurotransmitters and (2) the postsynaptic cell is in a depolarized state. Neurons Aand Csynapse onto neurons I and II. If activity in neurons Aand Ccoincides with either a depolarization or an action potential (which is a depolarization) in the postsynaptic cell, then LTP will be induced. For (e), neuron Cdoes not synapse onto neuron II.

Question 20

Why was the postsynaptic CA1 neuron voltage clamped to +30 mV? Select all that apply. A) To stimulate insertion of AMPA receptors into the postsynaptic membrane B) To move NMDA receptors into the synapse from an extrasynaptic site C) To cause coordination between the pre- and postsynaptic neuron D) To increase conductance of the NMDAR by removing the Mg²⁺ block E) To stimulate AMPA receptors, which in turn activate NMDA Rs

Accepted Answer

At rest, -60 mV, the NMDARs are blocked with Mg²⁺. When the postsynaptic cell was depolarized to +30 mV this removed the Mg²⁺ block, which resulted in the measured postsynaptic response.

Quiz 10: Memory, Learning, and Synaptic Plasticity

Why was AP5 applied while the neuron was held at +30 mV?

What is the basic circuitry of the hippocampus? A) Entorhinal cortex > __ (area) via the path B) (cell layer) to (cell layer) via the _ (pathway) C) ______ (cell layer) to _ (cell layer) via the ____ (pathway)

Which is true for spike-timing-dependent plasticity? Select all that apply.

The amnesic patient, H.M., lost the ability to store new memories, but could still remember events and people prior to his surgery. What kind of memory did he lose? Choose all that apply.

The amnesic patient, H.M., could still learn motor tasks, like learning to draw while looking in a mirror. What kind of memory is this? Choose all that apply.

What is synaptic plasticity?

Which is an example of associativity? Select all that apply.

Why is CaMKII a good candidate for a molecular memory molecule?

What is long-term potentiation?

What are 'silent synapses'? Select all that apply

Why does the NMDAR provide a good molecular mechanism for coincidence detection? Select the best answer.

How is LTD generated? Choose all that apply.

Which is an example of cooperativity? Select all that apply.

Why was the postsynaptic CA1 neuron voltage clamped to +30 mV? Select all that apply.

Quiz 10: Memory, Learning, and Synaptic Plasticity

Why was AP5 applied while the neuron was held at +30 mV?

What is the basic circuitry of the hippocampus? A) Entorhinal cortex > ______ (area) via the ________ path B) ________ (cell layer) to ______ (cell layer) via the ___ (pathway) C) __________ (cell layer) to _______ (cell layer) via the ______ (pathway)

Which is true for spike-timing-dependent plasticity? Select all that apply.

The amnesic patient, H.M., lost the ability to store new memories, but could still remember events and people prior to his surgery. What kind of memory did he lose? Choose all that apply.

The amnesic patient, H.M., could still learn motor tasks, like learning to draw while looking in a mirror. What kind of memory is this? Choose all that apply.

What is synaptic plasticity?

Which is an example of associativity? Select all that apply.

Why is CaMKII a good candidate for a molecular memory molecule?

What is long-term potentiation?

What are 'silent synapses'? Select all that apply

Why does the NMDAR provide a good molecular mechanism for coincidence detection? Select the best answer.

How is LTD generated? Choose all that apply.

Which is an example of cooperativity? Select all that apply.

Why was the postsynaptic CA1 neuron voltage clamped to +30 mV? Select all that apply.

What is the basic circuitry of the hippocampus? A) Entorhinal cortex > __ (area) via the path B) (cell layer) to (cell layer) via the _ (pathway) C) ______ (cell layer) to _ (cell layer) via the ____ (pathway)