Exam 10: Memory, Learning, and Synaptic Plasticity

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?

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?

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?

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?

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

What is synaptic plasticity?

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?

How is LTD generated? Choose 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 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

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

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?

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?

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 an example of associativity? Select all that apply.

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

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

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?

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?

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?