Chapter 29: Regeneration and Repair of Synaptic Connections after Injury

Test Bank

Type: multiple choice question

Title: Chapter 29 - Question 01

1. After an axon degenerates, which process takes the longest in the repair process?

Feedback: Subhead: Regeneration in the Peripheral Nervous System

Learning Objective: Describe the sequence of changes that occur when a sensory or motor axon in a vertebrate peripheral nerve is axotomized.

Bloom’s Level: 3. Applying

a. Macrophage recruitment

b. Axotomized neuron dying

c. Schwann cell de-differentiating

d. Endoplasmic reticulum dispersing

e. Myelin sheath degrading

Type: multiple choice question

Title: Chapter 29 - Question 02

2. What might slow the process of “dying back” of a motor neuron resulting from toxic insult?

Feedback: Subhead: Regeneration in the Peripheral Nervous System

Learning Objective: Describe the sequence of changes that occur when a sensory or motor axon in a vertebrate peripheral nerve is axotomized.

Bloom’s Level: 3. Applying

a. Regular muscle stimulation, such as that which occurs in physical therapy

b. Administration of a specific antitoxin or antidote

c. Pharmacological treatment of an antibody against the toxin or toxicant

d. Placement of electrodes on the skin overlying the muscle to provide constant stimulation

e. Administration of anti-inflammatory drugs

Type: multiple choice question

Title: Chapter 29 - Question 03

3. When an axon is severed, what likely causes the presynaptic cell to withdraw axons?

Feedback: Subhead: Regeneration in the Peripheral Nervous System

Learning Objective: Explain why axotomy can also cause changes in the presynaptic neurons that provide inputs to a damaged cell.

Bloom’s Level: 4. Analyzing

a. The postsynaptic neuron dying, initiating apoptotic cascades

b. The postsynaptic neuron condensing, and widening the synapse to pull axons away

c. Invading macrophages crowding into the synapse, effectively pushing the presynaptic neuron away

d. The de-differentiation of Schwann cells pulling the postsynaptic neuron away

e. Both the pre- and postsynaptic neurons expressing repulsive cues, such as Slit and its Robo receptor

Type: multiple choice question

Title: Chapter 29 - Question 04

4. When a tissue, such as a muscle membrane, is “super sensitive,” this means that it

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Describe three changes that can occur in denervated mammalian muscle fibers.

Bloom’s Level: 2. Understanding

a. requires more chemical stimulus to excite it than normal.

b. requires less chemical stimulus to excite it than normal.

c. takes longer to excite the tissue than it normally does.

d. takes shorter time to excite the tissue than it normally does.

e. has no relationship to the strength of the stimulus that excites the tissue in question.

Type: multiple choice question

Title: Chapter 29 - Question 05

5. If a muscle fiber has numerous nerve inputs, what will happen if 10% of those nerve inputs were severed?

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Describe three changes that can occur in denervated mammalian muscle fibers.

Bloom’s Level: 5. Evaluate

a. There will be no response.

b. Adjacent nerves will sprout to replace the 10% that was lost.

c. More nerves amounting to more than 10% will sprout.

d. Fewer nerves amounting to less than 10% will sprout.

e. It depends on the usual activity (workload) of the muscle.

Type: multiple choice question

Title: Chapter 29 - Question 06

6. Following denervation of a muscle, uniform recordings from a microelectrode along the entire muscle fiber means that

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Discuss the experimental evidence for the conclusion that denervation super sensitivity is produced by muscle inactivity.

Bloom’s Level: 4. Analysis

a. ACh receptors were both up-regulated and redistributed themselves along the muscle.

b. ACh receptors increased their affinity for acetylcholine at the end-plate.

c. the end-plate grew, thereby increasing the surface area, which could accommodate more ACh receptors.

d. end-plates became more numerous, covering a greater surface area of the muscle.

e. ACh was released from the presynaptic neuron in higher quantal yield.

Type: multiple choice question

Title: Chapter 29 - Question 07

7. The binding affinity of ACh for its fetal receptors at the site of innervation vs. that at the end-plate in adult muscle is likely because of the

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Discuss the experimental evidence for the conclusion that denervation super sensitivity is produced by muscle inactivity.

Bloom’s Level: 4. Analysis

a. sheer number of receptors that can occupy the respective sites.

b. different subunit composition of between the fetal and adult forms of the receptor.

c. density of the receptors at the site of innervation between the fetal and adult forms of the receptor.

d. size of the presynaptic terminal.

e. differences in surface area between the fetal and adult sites of innervation.

Type: multiple choice question

Title: Chapter 29 - Question 08

8. What might be a reason for the adult denervated muscle to express fetal ACh receptors?

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Discuss the experimental evidence for the conclusion that denervation super sensitivity is produced by muscle inactivity.

Bloom’s Level: 4. Analysis

a. The turnover rate of the adult ε subunit can be decreased.

b. The turnover rate of the α subunit can be decreased.

c. The turnover rate of the δ subunit can be increased.

d. The turnover rate of the α subunit can be increased.

e. When all subunits are expressed, it is easier to eliminate unnecessary ones than it is to add necessary ones.

Type: multiple choice question

Title: Chapter 29 - Question 09

9. If an experimenter wanted to slow down receptor turnover, one thing they can do is to increase cAMP levels and protein kinase A activity. This means that any subsequent changes in gene expression entails

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Discuss the experimental evidence for the conclusion that denervation super sensitivity is produced by muscle inactivity.

Bloom’s Level: 4. Analysis

a. increasing the expression of lysosomal enzymes.

b. decreasing the expression of lysosomal enzymes.

c. increasing the expression of fast-type calcium channels.

d. decreasing the expression of fast-type sodium channels.

e. increasing expression of the ACh receptor subunits.

Type: multiple choice question

Title: Chapter 29 - Question 10

10. Denervation super sensitivity is highly dependent on

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Discuss the experimental evidence for the conclusion that denervation super sensitivity is produced by muscle inactivity.

Bloom’s Level: 4. Analysis

a. ACh receptor number.

b. ACh receptor density.

c. sensitivity to ACh.

d. distance between the site of innervation and that of denervation.

e. strength of the current.

Type: multiple choice question

Title: Chapter 29 - Question 11

11. If you applied tiny amounts of ACh to muscle, you get excitatory postsynaptic potentials (epsps) on individual muscle fibers. When a muscle is stimulated, however, action potentials are also fired and obscure the epsps. What manipulation can be done to mask the action potentials, thereby revealing the underlying epsps?

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Discuss the experimental evidence for the conclusion that denervation super sensitivity is produced by muscle inactivity.

Bloom’s Level: 4. Analysis

a. The application of tiny amounts of ACh

b. The application of tiny amounts of tetrodotoxin

c. The application of tiny amounts of curare

d. The application of substantial amounts of ACh

e. The application of substantial amounts of sodium

Type: multiple choice question

Title: Chapter 29 - Question 12

12. Calcium influx into the muscle is directly caused by

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Explain how intracellular calcium contributes to the development of denervation super sensitivity.

Bloom’s Level: 2. Understanding

a. agrin binding to its receptor.

b. sodium influx.

c. increased ACh receptor expression.

d. increased calcium channel expression.

e. potassium leakage.

Type: multiple choice question

Title: Chapter 29 - Question 13

13. To maintain a constant steady-state high sensitivity level of muscle ACh,

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Explain how intracellular calcium contributes to the development of denervation super sensitivity.

Bloom’s Level: 3. Applying

a. muscle must be constantly active.

b. muscle must undergo intermittent naturally occurring denervation.

c. ACh receptors must cluster as discrete sites at the end-plates.

d. ACh receptors must reliably turnover (be regularly synthesized and degraded).

e. Acetylcholinesterase must be inhibited.

Type: multiple choice question

Title: Chapter 29 - Question 14

14. Although the growth factors, BDNF and NGF, and the ApoE and LIF secreted by Schwann cells and macrophages promote neuronal survival, many other such cytokines can also collect at the site of injury. Such a gathering of these molecules is a normal physiological response to injury but can also inhibit axon re-innervation. This response is called

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Explain how Schwann cells and microglia contribute to axon regeneration.

Bloom’s Level: 3. Applying

a. blood clotting.

b. recruitment.

c. inflammation.

d. apoptosis.

e. sprouting.

Type: multiple choice question

Title: Chapter 29 - Question 15

15. To help regenerate axons, Schwann cells express copious amounts of BDNF and NGF receptors so that the

Feedback: Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Explain how Schwann cells and microglia contribute to axon regeneration.

Bloom’s Level: 4. Analyzing

a. Schwann cells can better survive.

b. Schwann cells can find their place along the axon.

c. Schwann cells can participate in the inflammation process.

d. axon can recruit the Schwann cells to myelinate the former.

e. axon can use the neurotrophins as guidance clues to help them find their postsynaptic target.

Type: multiple choice question

Title: Chapter 29 - Question 16

16. Evidence points to _______ as a key ingredient in the basal lamina that allows synapses to regenerate following cutting of the nerve and muscle fibers.

Feedback: Subhead: Basal Lamina, Agrin, and the Function of Synaptic Specializations

Learning Objective: Describe the role of the synaptic basal lamina in the regeneration of neuromuscular synapses.

Bloom’s Level: 3. Applying

a. agrin

b. acetylcholine

c. acetylcholine receptors

d. acetylcholinesterase

e. nerve growth factor

Type: multiple choice question

Title: Chapter 29 - Question 17

17. Synapse elimination means that the presynaptic axon will first

Feedback: Subhead: Basal Lamina, Agrin, and the Function of Synaptic Specializations

Learning Objective: Outline the steps by which a damaged axon in the peripheral nervous system of an adult mammal regrows to restore sensory and motor functions.

Bloom’s Level: 3. Applying

a. atrophy.

b. withdraw.

c. be phagocytized by nearby astrocytes.

d. be crowded out by existing surviving presynaptic and postsynaptic neurons, forming new synapses.

e. lyse.

Type: multiple choice question

Title: Chapter 29 - Question 18

18. Suppose an α-motor neuron had five axons, which we will call a, b, c, d, and e synapsing onto a muscle with two fibers (“1” and “2”). Axons a and b innervated muscle fiber 1, while axons c, d, and e innervated muscle fiber 2. Then, axons c and d were severed. What result is likely?

Feedback: Subhead: Basal Lamina, Agrin, and the Function of Synaptic Specializations

Learning Objective: Outline the steps by which a damaged axon in the peripheral nervous system of an adult mammal regrows to restore sensory and motor functions.

Bloom’s Level: 6. Creating

a. Axons c and d would regrow to synapse with muscle fiber 2, restoring their original connections.

b. Axons a and b would withdraw.

c. Axons c and/or d would regrow to synapse with muscle fiber 1, while axon a and/or b withdraws.

d. Axons and/or b would withdraw and synapse with muscle fiber 2.

e. Axons a and b would remain unaffected.

Type: multiple choice question

Title: Chapter 29 - Question 19

19. If you had a transgenic mouse in which the agrin gene was knocked out, which of the following would your mouse not be able to do?

Feedback: Subhead: Basal Lamina, Agrin, and the Function of Synaptic Specializations

Learning Objective: Explain how agrin induces the formation of postsynaptic specializations.

Bloom’s Level: 3. Applying

a. Form neuromuscular synapses

b. Survive past birth

c. Coordinate movements, such as walking

d. Cluster acetylcholine receptors

e. Myelinate axons

Type: multiple choice question

Title: Chapter 29 - Question 20

20. If you had a transgenic mouse in which the rabsyn gene was knocked out, which of the following would your mouse not be able to do?

Feedback: Subhead: Basal Lamina, Agrin, and the Function of Synaptic Specializations

Learning Objective: Explain how agrin induces the formation of postsynaptic specializations.

Bloom’s Level: 3. Applying

a. Form neuromuscular synapses

b. Survive past birth

c. Coordinate movements, such as walking

d. Cluster acetylcholine receptors

e. Myelinate axons

Type: multiple choice question

Title: Chapter 29 - Question 21

21. In the acetylcholine receptor clustering process, which of the following lasts the longest?

Feedback: Subhead: Basal Lamina, Agrin, and the Function of Synaptic Specializations

Learning Objective: Explain how agrin induces the formation of postsynaptic specializations.

Bloom’s Level: 3. Applying

a. MuSK phosphorylation

b. Acetylcholine receptor phosphorylation

c. Acetylcholine receptor movement and clustering

d. Agrin binding to Lrp4

e. Recruitment of ACh receptors aggregates

Type: multiple choice question

Title: Chapter 29 - Question 22

22. Neuronal regeneration in the adult mammalian CNS does not occur as easily as it does in the immature mammalian CNS because

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Compare neuronal regeneration and repair in the adult and immature mammalian CNS.

Bloom’s Level: 3. Applying

a. there are more excitatory factors/neurotransmitters in the immature CNS than in the adult.

b. there are more inhibitory factors/neurotransmitters in the immature CNS than in the adult.

c. adult CNS axons have more myelination than that of immature CNS.

d. adult CNS neurons are fully differentiated, compared to that of immature CNS.

e. adult CNS is less permissive overall than is the immature CNS.

Type: multiple choice question

Title: Chapter 29 - Question 23

23. Because axons in the immature mammalian CNS are not yet myelinated, these neurons are more amenable to regeneration. Which of the following properties of myelin, therefore, would be responsible in preventing such regeneration from occurring?

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Compare neuronal regeneration and repair in the adult and immature mammalian CNS.

Bloom’s Level: 3. Applying

a. Insulating properties against action potential propagation

b. Physical barrier to axons that are elongating

c. Myelin’s basic protein

d. The propagation of inhibitory potentials

e. Lowered neuronal resting membrane potential

Type: multiple choice question

Title: Chapter 29 - Question 24

24. In a complete spinal cord injury, one of the major impediments to functional recovery is

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Describe how the effects of anatomically incomplete spinal cord injury differ from those of anatomically complete spinal cord injury.

Bloom’s Level: 3. Applying

a. destruction of permissive environments.

b. compromised blood brain barrier.

c. increased expression of inhibitory factors.

d. enhanced gliosis and glial scarring.

e. decreased expression of growth and survival factors.

Type: multiple choice question

Title: Chapter 29 - Question 25

25. In an incomplete spinal cord injury (as opposed to a complete spinal cord injury), one of the most obvious effects is

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Describe how the effects of anatomically incomplete spinal cord injury differ from those of anatomically complete spinal cord injury.

Bloom’s Level: 2. Understanding

a. recovery of motor function.

b. recovery of sensory function.

c. spontaneous recovery of motor function.

d. spontaneous recovery of sensory function.

e. rapid spontaneous recovery of motor function.

Type: multiple choice question

Title: Chapter 29 - Question 26

26. A patient who has just been through a terrible car accident presents in the emergency room unable to feel or move his legs. The ER surgeon suspects spinal cord damage at the lower lumbar level. To minimize the probability that this patient will be paralyzed for life, the physician should

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Give two explanations why regeneration typically fails in the adult mammalian CNS.

Bloom’s Level: 3. Applying

a. wait and see, just making sure that the patient remains immobile.

b. relieve swelling by administration of anti-inflammatory drugs.

c. administer anti-inflammatory drugs after a week or two has passed.

d. administer antibodies against the proteins that are known to regulate and inhibit neural growth.

e. administer antibodies against the proteins released by glial cells contributing to scar tissue.

Type: multiple choice question

Title: Chapter 29 - Question 27

27. Why would inhibition of Nogo likely not result in full recovery of locomotor function following spinal cord injury?

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Give two explanations why regeneration typically fails in the adult mammalian CNS.

Bloom’s Level: 5. Evaluating

a. The complexity of even a simple axotomy is too high that recovery is dependent on a plethora of factors, as well as on the timing of when these factors are active.

b. How Nogo is inhibited, whether by a drug or an antibody, is critical whether full recovery occurs.

c. Nogo is not expressed in amounts high enough that would impact full recovery.

d. Nogo receptors are not expressed in high enough amounts that would impact full recovery.

e. Nogo binds to its receptor with relatively low affinity.

Type: multiple choice question

Title: Chapter 29 - Question 28

28. In a spinal cord injury, if the concentration and variety of neuroprotective and neurotrophic factors outweighs those of neural inhibitory factors full recovery

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain why reactive glial cells are referred to as a “double-edged sword.”

Bloom’s Level: 4. Analyzing

a. is imminent.

b. is likely.

c. may still not occur.

d. will not occur.

e. cannot be known for sure.

Type: multiple choice question

Title: Chapter 29 - Question 29

29. Following spinal cord injury, one of the best ways to help ensure that recovery of function occurs is a(n)

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain why reactive glial cells are referred to as a “double-edged sword.”

Bloom’s Level: 3. Applying

a. aggressive battery of anti-inflammatory drugs.

b. aggressive battery of anti-depressant drugs.

c. reliable and challenging physical therapy regimen.

d. combination of anti-inflammatory drug regimen and physical therapy.

e. combination of anti-inflammatory and antidepressant drug regimen plus physical therapy.

Type: multiple choice question

Title: Chapter 29 - Question 30

30. What is a plausible reason that, as a treatment, regularly ablating the glial scar will still not result in full recovery of function in a spinal cord injury?

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain why reactive glial cells are referred to as a “double-edged sword.”

Bloom’s Level: 3. Applying

a. Such surgery would deplete neurotrophic and neuroprotective factors.

b. Reactive glial cells will increase scars and gliosis in response to such an intervention.

c. Reactive glial cells will increase their proliferation and therefore, the scars and gliosis in response to such an intervention.

d. The correct timing of when to ablate the scar is unknown.

e. The correct amount to ablate is unknown.

Type: multiple choice question

Title: Chapter 29 - Question 31

31. One important reason for why olfactory ensheathing glial cells have been investigated as candidates for cell transplant experiments, such as in the spinal cord, is because these cells

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Discuss why olfactory ensheathing glial cells have been investigated as candidates for cell transplant experiments.

Bloom’s Level: 3. Applying

a. are easily accessible by researchers.

b. are unique to the olfactory system, where the neurons are constantly replaced throughout life.

c. are easy to manipulate in culture.

d. express high concentrations of neurotrophic factors.

e. are capable of warding off gliosis in the event of injury.

Type: multiple choice question

Title: Chapter 29 - Question 32

32. If one were to transplant olfactory neurons and their ensheathing glial cells at the lesion site in a spinal cord injury, full recovery would likely still not occur because

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Discuss why olfactory ensheathing glial cells have been investigated as candidates for cell transplant experiments.

Bloom’s Level: 6. Creating

a. the spinal cord histology is too dissimilar to that of the olfactory bulb.

b. different intracellular signaling pathways exist in the olfactory bulb as opposed to that of the spinal cord.

c. olfactory neurons are too fragile for such transplant procedures.

d. olfactory neuron re-growth in their new environment lasts for only a short time.

e. ensheathing glial cells die off almost immediately upon being transplanted into their new spinal cord environment, because the latter has too many inhibitory factors associated with large amounts of myelin.

Type: multiple choice question

Title: Chapter 29 - Question 33

33. For a peripheral nerve bridge to be successful, which of the following must occur?

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain why grafts using a peripheral nerve bridge are successful in some circumstances but not in others.

Bloom’s Level: 3. Applying

a. The environment into which the axon is growing must be permissive.

b. The neuron whose axon is extending must be of the same type as those occupying the environment in which they will grow.

c. The growing axon has a limit of only 2 mm.

d. The growing axons must be capable of both anterograde and retrograde transport of proteins.

e. The peripheral nerve bridge must come from the same animal into which a transplant is to be made; i.e., an auto-transplant.

Type: multiple choice question

Title: Chapter 29 - Question 34

34. Assuming a permissive environment, which intrinsic signaling pathway would most likely not promote successful axon elongation?

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain why grafts using a peripheral nerve bridge are successful in some circumstances but not in others.

Bloom’s Level: 3. Applying

a. MAPK

b. PI3K

c. PKA

d. JAK/STAT

e. Apoptotic cascades

Type: multiple choice question

Title: Chapter 29 - Question 35

35. Intrinsic repair strategies will rely on being able to manipulate the expression profile of proteins involved in both growth-promotion and growth inhibition. One of the most promising ways to target such intrinsic repair strategies so that growth is favored would be to focus on

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Compare the recovery and repair strategies for complete and incomplete spinal cord injuries.

Bloom’s Level: 3. Applying

a. prevention of injury.

b. diet.

c. timing of treatment following an injury—the sooner, the better.

d. epigenetics

e. type of treatment.

Type: multiple choice question

Title: Chapter 29 - Question 36

36. One of the major differences between an incomplete and a complete spinal cord injury or trans-section is that in the former

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Compare the recovery and repair strategies for complete and incomplete spinal cord injuries.

Bloom’s Level: 2. Understanding

a. there is a greater reliance on glial recruitment of cytokines.

b. there is a greater reliance on surviving neuronal axons reorganizing the circuits.

c. there is a greater reliance on physical therapeutic interventions.

d. grafting neural stem cells at the site of injury is more critical.

e. glial scarring represents a major barrier to complete recovery.

Type: multiple choice question

Title: Chapter 29 - Question 37

37. In a human complete spinal cord injury, _______ would be an appropriate type of cell to graft at the site of the lesion.

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Compare the recovery and repair strategies for complete and incomplete spinal cord injuries.

Bloom’s Level: 3. Applying

a. sciatic neurons

b. spinal cord neurons

c. cerebellar Purkinje neurons

d. olfactory neurons

e. stem cells

Type: multiple choice question

Title: Chapter 29 - Question 38

38. One of the major impediments of successful full recovery of function following implantation of neural stem cells is that

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain what is meant by the “neuronal relay strategy.”

Bloom’s Level: 3. Applying

a. such a strategy works only for physical trauma-based damage (e.g., spinal cord injury), rather than for neurodegenerative diseases (e.g., Alzheimer’s).

b. such a strategy works only for neurodegenerative diseases (e.g., Alzheimer’s), rather than for physical trauma-based damage (e.g., spinal cord injury).

c. often, neural stem cells fail to adapt to their new host environment.

d. often, the compromised host environment can affect the graft of the stem cells, disabling the latter.

e. neural stem cells must be of the correct phenotype.

Type: multiple choice question

Title: Chapter 29 - Question 39

39. The basic aim of transplanting neural stem cells into the adult mammalian CNS is to

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: State what is the basic aim for neurons that are transplanted into the adult mammalian CNS.

Bloom’s Level: 3. Applying

a. treat a neurodegenerative disease or CNS injury.

b. treat inflammation in the CNS.

c. treat peripheral diseases, such as diabetes, which are known to affect CNS functioning.

d. enhance epigenetic approaches to treat CNS disease or injury.

e. rewrite the genetic programming in CNS neurons as part of the therapeutic regimen against CNS disease or injury.

Type: multiple choice question

Title: Chapter 29 - Question 40

40. What is the best kind of cells to transplant into the adult mammalian CNS?

Feedback: Subhead: Regeneration in the Mammalian CNS

Learning Objective: State what is the basic aim for neurons that are transplanted into the adult mammalian CNS.

Bloom’s Level: 5. Evaluating

a. Adult neurons of the same phenotype as those occupying the area into which the transplant will be made

b. Young neurons (1-2 days postnatal) of the same phenotype as those occupying the area into which the transplant will be made

c. Neurons from the autonomic nervous system

d. Neural stem cells

e. Late embryonic neurons

Type: essay/short answer question

Title: Chapter 29 - Question 41

41. If the axon of a postsynaptic neuron is axotomized, explain what occurs with the presynaptic neuron after it has retracted.

Feedback: If the neuron whose axon was severed does not regenerate, it will die. Then, the presynaptic neuron can send its axon to make synaptic contact with neighboring surviving neurons.

Subhead: Regeneration in the Peripheral Nervous System

Learning Objective: Explain why axotomy can also cause changes in the presynaptic neurons that provide inputs to a damaged cell.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 29 - Question 42

42. What are the pros and cons of severing an axon close to, as opposed to far from, its soma?

Feedback: Of the cut occurred closer to the soma, there is greater access to cellular machinery (e.g., RER, Golgi) and shorter distance that anterograde transport must occur; on the other hand, the axon length is greater to repair. Farther away from the soma and closer to the target mans a greater distance for anterograde transport of vital materials (vesicles filled with proteins), but with less axon to regenerate and repair.

Subhead: Regeneration in the Peripheral Nervous System

Learning Objective: Explain why axotomy can also cause changes in the presynaptic neurons that provide inputs to a damaged cell.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 29 - Question 43

43. Propose an explanation for denervation super sensitivity to ACh.

Feedback: Denervation supersensitivity results in a redistribution, rather than a decrease, of ACh receptors. Denervation might have had a retrograde effect on gene expression, altering the complement, type or arrangement of cytoskeletal proteins known to anchor receptors in the plasma membrane, resulting in increased ability of receptors to migrate laterally within the membrane and distributing themselves anywhere, rather than at postsynaptic clusters (e.g., endplate). Such altered gene expression might also down-regulate acetylcholinesterase.

Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Describe three changes that can occur in denervated mammalian muscle fibers.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 29 - Question 44

44. Propose an explanation for why if a cut motor nerve is placed on an intact or innervated muscle, no new endplates will form, whereas if the muscle has been denervated or its endplate blocked by a-bungarotoxin, new endplate synapses will form.

Feedback: It is possible that the denervated or blocked muscle represents a permissive environment, releasing the appropriate amounts and types of growth factors and/or inhibition of inhibitory factors, thereby allowing new synapses to form. A functional innervated muscle, however, is less permissive as it may not need any more stimulation.

Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Describe three changes that can occur in denervated mammalian muscle fibers.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 29 - Question 45

45. If muscle is kept immobile, such as that which occurs with a broken limb confined inside a cast, explain why axons may not increase sprouting.

Feedback: A broken limb usually means that the bone, rather than the muscle or nerves, is damaged. So, because there has been no denervaton, there is no pressing need to compensate for the damage and therefore, there is no increased release of growth factors, cytokines, etc. Immobility will just decrease the stimulation of motor units; hence they only usual consequence is muscle and nerve atrophy, the latter if which, may entail some axonal retraction.

Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Describe three changes that can occur in denervated mammalian muscle fibers.

Bloom’s Level: 6. Creating

Type: essay/short answer question

Title: Chapter 29 - Question 46

46. Briefly describe an experiment to determine whether Ca²⁺ influx is critical for muscle contraction.

Feedback: Three separate experiments can be performed: (1) Culture muscle cells and then expose to ethylene-diamine-tetraacetic acid (EDTA) to sequester Ca²⁺. (2) Mutate specific amino acids in the voltage-gated calcium channels to determine whether contraction still occurs. (3) Produce RNAi of voltage-gated calcium channels to determine whether contraction still occurs.

Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Explain how intracellular calcium contributes to the development of denervation.

Bloom’s Level: 6. Creating

Type: essay/short answer question

Title: Chapter 29 - Question 47

47. Apolipoprotein E (ApoE) is a well-known genetic risk factor for a multitude of neurodegenerative diseases, such as Parkinson’s and Alzheimer’s. Explain, then, how ApoE is not only neuroprotective against oxidative damage, but also promotes neurite extension and adhesion.

Feedback: ApoE helps clear aggregation of β-amyloid (a toxic protein that impedes neurotransmission), but is also part of Schwann cell basal lamina.

Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Explain how Schwann Cells and microglia contribute to axon regeneration.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 29 - Question 48

48. Compare the clustering of ACh receptors in fetal muscle vs. adult muscle endplate. What is the advantage of the adult form of ACh clustering in the muscle endplate?

Feedback: Junctional folds in the adult muscle endplate allow for increased surface area, thereby allowing for higher density/numbers of ACh receptors per square area than in the fetal muscle.

Subhead: Effects of Denervation on Postsynaptic Cells

Learning Objective: Not aligned

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 29 - Question 49

49. Propose an explanation for how the basal lamina in the neuromuscular junction promotes synapse regeneration.

Feedback: One of the key proteins in the basal lamina is laminin, which binds both agrin and dystroglycan, which, in turn, binds directly to ACh receptors. Laminin may act as a bridge between the proteoglycan-rich substrate of the basal lamina and postsynaptic cell.

Subhead: Basal Lamina, Agrin, and the Formation of Synaptic Specializations

Learning Objective: Describe the role of the synaptic basal lamina in the regeneration of neuromuscular synapses.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 29 - Question 50

50. Explain the sequence of events in which agrin leads to the phosphorylation of ACh receptors.

Feedback: Agrin binds to Lrp4, leading to the phosphorylation of MuSK, which, in turn, interacts with the adaptor protein Dok7, ultimately leading to rapsyn binding phosphorylated ACh receptors, leading to their clustering.

Subhead: Basal Lamina, Agrin, and the Formation of Synaptic Specializations

Learning Objective: Explain how agrin induces the formation of postsynaptic specializations.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 29 - Question 51

51. In a microarray mRNA screening experiment, which showed that growth-promoting molecules and their receptors were over-expressed, while growth-inhibiting molecules and their receptors were under-expressed in 9-day-old animal, but the reverse occurred in 12-day-old animals, explain what more conclusive experiment should be done.

Feedback: Because timing and amount of transcripts do not always correlate with timing and amount of the corresponding protein, the latter should be evaluated.

Subhead: Regeneration in the Mammalian CNS

Learning Objective: Compare neuronal regeneration and repair in the adult and immature mammalian CNS.

Bloom’s Level: 6. Creating

Type: essay/short answer question

Title: Chapter 29 - Question 52

52. Explain why in a complete spinal cord injury, there is virtually no hope that the patient will ever functionally recover, whereas in an incomplete spinal cord injury, there is a possibility of some functional recovery.

Feedback: In a complete spinal cord injury, all axons are severed or, at least, severely damaged. Surgically implanted grafts of neural stem cells (which may not survive) and/or something that can mitigate glial scarring are the patient’s only hope. In an incomplete spinal cord injury, however, many (or some) axons have been spared. These propriospinal connections can form new connections, leading to spontaneous recovery. The caveat, however, is that experimentally, in mice, locomotor function was largely restored only if multiple lesions were made at different times. In a human with an incomplete spinal cord injury, however, multiple injuries usually do not occur.

Subhead: Regeneration in the Mammalian CNS

Learning Objective: Describe how the effects of anatomically incomplete spinal cord injury differ from those of anatomically complete spinal cord injury.

Bloom’s Level: 5. Evaluating

Type: essay/short answer question

Title: Chapter 29 - Question 53

53. Briefly explain how epigenetic mechanisms can influence peripheral nerve regeneration.

Feedback: In younger animals, the influence of epigenetics has not yet had enough time to influence physiology and behavior; thus, the only influences are genetic. As the animal ages, however, genetics plays a smaller role, while lifestyle variables (e.g., amount and type of exercise, drugs, diet) gain greater influence on gene expression. The role of neurons and their connections in adult animals, therefore, is not as plastic, cannot be influenced as much, and cannot be repaired as easily.

Subhead: Regeneration in the Mammalian CNS

Learning Objective: Give two explanations for why regeneration typically fails in the adult mammalian CNS

Bloom’s Level: 5. Evaluating

Type: essay/short answer question

Title: Chapter 29 - Question 54

54. Briefly explain why a peripheral nerve bridge would have marginal success in repairing spinal cord injury.

Feedback: Because these are adult mammalian CNS neurons, there is already firmly entrenched inhibitory factors, such as myelin, extracellular matrix, as well as intrinsic inhibitory pathways, glial scar tissue that are already in place.

Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain why grafts using a peripheral nerve bridge are successful in some circumstances but not in others.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 29 - Question 55

55. Although the Neuronal Relay Strategy can be applied to injury or disease, would it be possible to implement it in a healthy brain to enhance certain functions, such as learning and memory, central blindness or deafness?

Feedback: Probably not to enhance learning or memory, as there is no anatomic and functional deficit in cases where faster learning is wanting. Further, learning and memory are so complex, comes in so many different forms and occur in multiple sites throughout the brain (e.g., hippocampus, cerebral cortex, cerebellum, basal ganglia), that one cannot be sure that one is implanting neural stem cells in the correct site. It may be possible to ameliorate blindness or deafness using the neuronal relay strategy.

Subhead: Regeneration in the Mammalian CNS

Learning Objective: Explain what is meant by the neuronal relay strategy.

Bloom’s Level: 6. Creating