Question 1

For the graph on the right, the anterior cingulate cortex (ACC) was inactivated with lidocaine 1, 3, 18, and 36 days after fear conditioning training. What happened to these rats compared with the controls?

Accepted Answer

When the ACCwas lesioned 18 and 38 days after training the rats spent much less time freezing, which suggests that they had forgotten the association between location and shock.

Question 2

Taking together the results in Figure Q10-37, what is the interpretation of these results?

Accepted Answer

The answer of Taking together the results in Figure Q10-37,...

Question 3

Figure Q10-23 shows an example of endocannabinoid modulation of synaptic strength after high frequency stimulation (indicated by the horizontal bar above the large amplitude activity) to the presynaptic CA3 neurons. What would happen to the response if the CB1 receptors were blocked?  Figure Q10-23

Accepted Answer

If the endocannabinoid receptors are blocked, the retrograde signal would be blocked and therefore the depolarization-induced suppression of the presynaptic inhibition would be removed. This would result in a lack of change of spontaneous transmitter release in the presynaptic neuron.

Question 4

The Morris water maze has been used to test learning and memory in rodents. In
AandB there is a hidden platform (the large dot ) and the rat learns where the platform is located. In
C andD  the platform has been removed and the rat must remember where the platform was located (its location prior to removal is indicated by the large dot ). Which responses would be similar to a mouse in which CREB was selectively blocked in hippocampal CA1 neurons?

Accepted Answer

The answer of The Morris water maze has been used...

Question 5

The neural circuitry underlying the gill-withdrawal reflex is known: A sensory neuron in the gill synapses onto a motor neuron that innervates the gill. What is a neural mechanism for habituation?

Accepted Answer

With repeated stimulation of the sensory neuron, the synaptic strength between the pre- and postsynaptic neuron decreases which results in a decrease in the synaptic response in the motor neuron and a smaller response in the gill. The action potential response in the sensory neuron does not change and still follows siphon stimulation. Transmitter release in the motor neuron and response in the muscle is also not affected.

Question 6

For the left graph, rats were given a shock when they were placed in a specific environment. After they associated the shock with the environment, their hippocampus was removed at different intervals (7, 14, and 28 days after training). What happened to the rats with hippocampal lesions, compared to controls?

Accepted Answer

The longer the investigators waited to lesion the hippocampus, the more time the rats spent freezing, suggesting the rats remembered the location they received the shock.

Question 7

In 2000, Eric Kandel received the Nobel Prize in Physiology and Medicine, along with two other people for their "discoveries concerning signal transduction in the nervous system." Most of Kandel's work uncovered the contributions of the cAMP signal transduction pathway in memory formation in Aplysia. Why are the discoveries in Aplysia so important for our molecular understanding of learning and memory?
Where Does Learning Occur, and Where Is Memory Stored in the Brain?

Accepted Answer

The answer of In 2000, Eric Kandel received the Nobel...

Question 8

Hebb's postulate from 1949 states "When an axon of cell A is near enough to excite cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A's efficiency, as one of the cells firing B, is increased." Give an example of how synaptic plasticity results in:
A. Growth processes
B. Metabolic changes
What Is the Relationship Between Learning and Synaptic Plasticity?

Accepted Answer

The answer of Hebb's postulate from 1949 states "When an...

Question 9

Figure Q10-21 demonstrates spike-timing dependent activity.  Figure Q10-21
A. What is the approximate change in EPSC amplitude when the presynaptic input occurs 60 ms prior to the postsynaptic action potential?
B. What is the approximate change in EPSC amplitude when the presynaptic input occurs 10 ms before the postsynaptic action potential?

Accepted Answer

The answer of Figure Q10-21 demonstrates spike-timing dependent activity. ...

Question 10

The hippocampus is not essential for long-term memory storage. Defend this statement with reference to the human patient H.M.
Questions 10-37, 10-38, 10-39, and 10-40 refer to Figure Q10-37. Figure Q10-37 shows evidence for neocortical contributions to long-term storage in explicit memory.  Figure Q10-37

Accepted Answer

The answer of The hippocampus is not essential for long-term...

Question 11

What was one of the conclusions from this experiment?

Accepted Answer

The hippocampus is required for short-term memory but is not required for long-term memory retrieval. If there was a delay of 1days after training the animals could still remember the task. Therefore, since the hippocampus has been lesioned it cannot be involved in memory storage.

Question 12

What are some of the challenges in linking correlation of changes in synaptic strength in the hippocampus to causations of learning and memory? Briefly describe one experiment that has provided a better link between correlation and causation.

Accepted Answer

The answer of What are some of the challenges in...

Question 13

Figure Q10-29 shows short- and long-term memory in Aplysia using the gill withdrawal reflex.  Figure Q10-29
A. What would happen to the 4 single shock response if cAMP was inhibited?
B. What would happen to the 4 single shock response if CREB was inhibited?
C. What would happen to the 4 days, 4 trains per day response if CREB was inhibited?

Accepted Answer

The answer of Figure Q10-29 shows short- and long-term memory...

Question 14

Dopamine neurons in the VTA synapse onto neurons in the nucleus accumbens. Neurons in the VTA are dopaminergic and is has been hypothesized that dopaminergic neurons signal reward prediction error. In this hypothesis the actual reward is compared with the predicted reward. If these two things are not equal dopaminergic signals change the predicted reward so that it matches the actual reward.  Figure Q10-42
A. Figure Q10-42 shows a recording from a VTA dopaminergic neuron in a monkey. What happened when only the juice was presented to the animal prior to training? Was the predicted reward similar to the actual value? Explain your answer.
B. After training of a light to predict the amount of juice, what happened to the response to juice and why?
C. The juice was then NOT given to the monkey after it was predicted by the light. What happened and what is the reason for this response based on the abstract circuit model?

Accepted Answer

The answer of Dopamine neurons in the VTA synapse onto...

Question 15

Aplysia display many forms of learning including habituation and sensitization. If the siphon is touched, the gill withdraws. How is habituation of this reflex generated?

Accepted Answer

Habituation of a response is the reduction in a response to a stimulus that occurs frequently at the same strength. If the siphon is continually stimulated the gill withdrawal reflex will be reduced.

Question 16

The advantage of working with Drosophila is that molecular pathways underlying synaptic plasticity and learning can be identified. When investigators screened for Drosophila with defects in learning and memory they found several, including dunce and rutabaga. What proteins do these genes encode?

Accepted Answer

Dunce encodes a phosphodiesterase and rutabaga encodes an adenylate cyclase.

Question 17

Assume we can record spatially related neural activity from the entorhinal cortex and hippocampus of human. You are on vacation in London and have a map to find the Tower of London (you also do not have a smartphone).
A. What spatially related activity would you see in the entorhinal cortex as you are walking around London with your map with Cartesian coordinates?
B. What activity pattern would you see in the hippocampus as you were moving toward your destination?
C. Once you arrived at the Tower of London you find you need to move to the gate that is in the neighboring wall and so you have to walk along one wall of a building. What activity pattern would you see in the entorhinal cortex?

Accepted Answer

The answer of Assume we can record spatially related neural...

Question 18

According to the circuit diagram in Figure Q10-41, why does lesioning the amygdala disrupt contextual and fear conditioning whereas hippocampal lesions only disrupt contextual conditioning?  Figure Q10-41

Accepted Answer

The answer of According to the circuit diagram in Figure...

Question 19

Figure Q10-31 shows the circuitry and molecular cascade underlying olfactory learning in Drosophila. The CS is the odor and the US is the shock.  Figure Q10-31
A. Why does the US paired with the CS result in olfactory conditioning?
B. Why would a different odorant not result in olfactory conditioning?
C. How could you test whether increases in the cAMP pathway in the mushroom body neurons contribute to olfactory conditioning?
D. Based on what is shown in Aplysia, what molecular pathway could contribute to long-term memory formation?

Accepted Answer

The answer of Figure Q10-31 shows the circuitry and molecular...

Question 20

Early experiences can shape neuronal circuitry and long-term memory. One example of this is the development of the auditory map in owls. Young owls were fitted with goggles that shifted their visual world. When the synaptic terminals of ICC to ICX were examined, owls raised with prisms had substantially expanded projections compared to owls raised without prisms. Based on this long-lasting change in neuronal connectivity, what do you think would happen if prisms were put back onto an adult owl that was initially reared with the prisms?

Accepted Answer

The answer of Early experiences can shape neuronal circuitry and...

Quiz 10: Memory, Learning, and Synaptic Plasticity