Test Bank Chapter 23 Touch, Pain, And Texture Sensation

Chapter 23: Touch, Pain, and Texture Sensation

Test Bank

Type: multiple choice question

Title: Chapter 23 Question 01

1. What morphological feature distinguishes between Pacinian and Ruffini receptors on one hand and Meissner and Merkel receptors on the other?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Differentiate between the two major classes of skin receptors.

Bloom’s Level: 1. Remembering

a. Pacinian and Ruffini structures tend to be larger than Meissner and Merkel structures.

b. Pacinian and Ruffini structures respond to mechanical stimuli, whereas Meissner and Merkel’s structures do not.

c. Pacinian and Ruffini structures are more sensitive to mechanical stimuli than Meissner and Merkel’s structures are.

d. Pacinian and Ruffini receptors are encased in a capsule, whereas Meissner and Merkel’s receptors are not.

e. Pacinian and Ruffini receptors are also sensitive to changes in temperature, whereas Meissner and Merkel receptors are not.

Type: multiple choice question

Title: Chapter 23 Question 02

2. Which two receptors tend to lie deeper in the skin?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Differentiate between the two major classes of skin receptors.

Bloom’s Level: 1. Remembering

a. Pacinian and Merkel

b. Pacinian and Meissner

c. Pacinian and Ruffini

d. Merkel and Meissner

e. Merkel and Ruffini

Type: multiple choice question

Title: Chapter 23 Question 03

3. Which receptors tend to adapt slowly to compression on the skin?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Differentiate between the two major classes of skin receptors.

Bloom’s Level: 1. Remembering

a. Pacinian and Merkel

b. Pacinian and Meissner

c. Pacinian and Ruffini

d. Merkel and Meissner

e. Merkel and Ruffini

Type: multiple choice question

Title: Chapter 23 Question 04

4. Which receptors will be stimulated when tickled?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Differentiate between the two major classes of skin receptors.

Bloom’s Level: 3. Applying

a. Pacinian

b. Meissner and free nerve endings

c. Ruffini endings

d. Merkel disks

e. Ruffini and free nerve endings

Type: multiple choice question

Title: Chapter 23 Question 05

5. Which two receptors tend to lie relatively close to the surface of the skin?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Name four different types of receptor complexes and state where they are located.

Bloom’s Level: 2. Understanding

a. Pacinian and Merkel

b. Pacinian and Meissner

c. Pacinian and Ruffini

d. Merkel and Meissner

e. Merkel and Ruffini

Type: multiple choice question

Title: Chapter 23 Question 06

6. Besides Meissner Corpuscles, which receptor will be affected by local anesthetics?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Name four different types of receptor complexes and state where they are located.

Bloom’s Level: 3. Applying

a. Pacinian

b. Merkel

c. Ruffini

d. Nociceptors

e. Free nerve endings

Type: multiple choice question

Title: Chapter 23 Question 07

7. When a hair is pulled out of the skin, it is painful. Which kind of receptor is stimulated?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Name four different types of receptor complexes and state where they are located.

Bloom’s Level: 3. Applying

a. Pacinian

b. Merkel and free nerve endings

c. Ruffini and free nerve endings

d. Free nerve endings

e. Meissner

Type: multiple choice question

Title: Chapter 23 Question 08

8. How long will it take for an action potential to reach the spinal cord if a receptor neuron’s skin receptors were in the toe? Assume that action potentials travel at a rate of 80 m/s and that the distance to be travelled is 0.6 m.

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Describe the three components of receptor neurons that innervate the skin of the hands, feet, arms, legs, and trunk.

Bloom’s Level: 3. Applying

a. 0.5 milliseconds

b. 1 millisecond

c. 7.5 milliseconds

d. 15 milliseconds

e. 48 milliseconds

Type: multiple choice question

Title: Chapter 23 Question 09

9. What part of the long receptors make synaptic contact with the secondary neurons that extend into the brain?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Describe the three components of receptor neurons that innervate the skin of the hands, feet, arms, legs, and trunk.

Bloom’s Level: 2. Understanding

a. The somas in the dorsal root ganglion

b. The axon hillock

c. The part that enters the spinal cord dorsal horn

d. The part that enters the spinal nerve

e. The part that enters the spinal cord intermediate zone

Type: multiple choice question

Title: Chapter 23 Question 10

10. The sensitivity of long receptors in the skin of various body parts in the periphery are determined by the

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Describe the three components of receptor neurons that innervate the skin of the hands, feet, arms, legs, and trunk.

Bloom’s Level: 2. Understanding

a. size of their receptive fields

b. number of terminal axons at the receptor

c. length of the axon between the receptor and the dorsal root ganglion

d. length of the axon between the dorsal root ganglion and spinal cord

e. number of somas in the dorsal root ganglion

Type: multiple choice question

Title: Chapter 23 Question 11

11. Microneurography can be used to map sensory receptive fields all over the body. Specifically, this technique can determine their

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Define microneurography and discuss what advantages it offers over animal investigations.

Bloom’s Level: 6. Creating

a. relative size.

b. number of receptors contained therein.

c. depth (how far under the skin it extends).

d. number of neighboring receptive fields.

e. innervation density.

Type: multiple choice question

Title: Chapter 23 Question 12

12. Microneurography can be used to map sensory receptive fields all over the body. This is a well-known way to diagnose and evaluate

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Define microneurography and discuss what advantages it offers over animal investigations.

Bloom’s Level: 4. Analyzing

a. multiple sclerosis.

b. Parkinson’s disease.

c. cerebral meningitis.

d. spinal cord injury.

e. traumatic brain injury.

Type: multiple choice question

Title: Chapter 23 Question 13

13. Besides the ability to provide verbal feedback, using microneurography on humans offers which other advantage over that if using other animals?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Define microneurography and discuss what advantages it offers over animal investigations.

Bloom’s Level: 3. Applying

a. Human skin is more sensitive than that of other animals.

b. Humans have a smaller surface area (skin)-to-volume ratio.

c. Human skin is thinner than that of other animals

d. Humans have little-to-no hair, the presence of which will confound the findings obtained in microneurography and must be shaved off if using other animals.

e. Ultimately, the goal is to be able to map the sensory receptive fields in humans; other animals are used when using humans is ethically, morally or legally inappropriate.

Type: multiple choice question

Title: Chapter 23 Question 14

14. Which nerve fibers will conduct action potentials the fastest?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Describe the two systems involved in processing pain signals.

Bloom’s Level: 4. Analyzing

a. Wide diameter, heavily myelinated

b. Wide diameter, thinly myelinated

c. Narrow diameter, heavily myelinated

d. Narrow diameter, thinly myelinated

e. Any diameter, not myelinated

Type: multiple choice question

Title: Chapter 23 Question 15

15. Suppose the Aδ fibers send action potentials at 10 m/sec and the unmyelinated C fibers sends them at 2 m/sec. How much time will elapse between first pain and second pain upon accidently dropping a heavy brick on your toe? Assume a total distance of 1.2 m from toe to spinal cord to somatosensory cortex.

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Describe the two systems involved in processing pain signals.

Bloom’s Level: 4. Analyzing

a. 25 milliseconds

b. 100 milliseconds

c. 120 milliseconds

d. 480 milliseconds

e. 600 milliseconds

Type: multiple choice question

Title: Chapter 23 Question 16

16. Although probably impossible to experiment with, a person is surprised by being struck with equal force in the face by two other people: one familiar (a loved one) and one complete stranger. The pain felt by the struck person is seems greater if (s)he is struck by the familiar person than if struck by the complete stranger. This subjective difference in sensation of these two identical forces is processed by the

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Describe the two systems involved in processing pain signals.

Bloom’s Level: 3. Applying

a. primary somatosensory cortex.

b. secondary somatosensory cortex.

c. somatosensory association cortex.

d. anterior cingulate cortex.

e. central sulcus.

Type: multiple choice question

Title: Chapter 23 Question 17

17. The placebo effect seems to work primarily through the

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Explain how placebo treatment works.

Bloom’s Level: 2. Understanding

a. anterior cingulate cortex.

b. somatosensory cortex.

c. thalamus.

d. brainstem.

e. insular cortex.

Type: multiple choice question

Title: Chapter 23 Question 18

18. What might be one possible reason or scenario in which the placebo treatment does not work in relieving pain?

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Explain how placebo treatment works.

Bloom’s Level: 5. Evaluating

a. Prior knowledge or awareness of the placebo effect

b. Overwhelming subjective feelings about the severity of the pain resulting from a serious injury, such as from an amputation

c. When enough anesthetics are used

d. When insufficient anesthesia is used

e. When only topical anesthetics are used

Type: multiple choice question

Title: Chapter 23 Question 19

19. Blockade of µ-opioid receptors is correlated with suppression of activity in the anterior cingulate and insular cortices. This can be experimentally confirmed by administration of a µ-opioid receptor

Feedback: Subhead: From Receptors to Cortex

Learning Objective: Explain how placebo treatment works.

Bloom’s Level: 4. Analyzing

a. antagonist and subsequent visualization via fMRI.

b. antagonist and simultaneous visualization via fMRI.

c. agonist, such as morphine, followed by visualization via fMRI.

d. antagonist, accompanied by administration of a µ-opioid receptor agonist, such as morphine, and simultaneous visualization via fMRI.

e. antagonist, accompanied by administration of a µ-opioid receptor agonist, such as morphine, followed by visualization via fMRI.

Type: multiple choice question

Title: Chapter 23 Question 20

20. Although a surface topographic map of the sensory inputs is used to illustrate the disproportionate amount of somatosensory cortex devoted to whiskers, it is more valid to evaluate the underlying cortical ________ of such input.

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Describe the basic organization of the somatosensory cortex in rats and mice.

Bloom’s Level: 5. Evaluating

a. density

b. organization

c. depth

d. volume

e. activity

Type: multiple choice question

Title: Chapter 23 Question 21

21. In rats and mice, a single whisker projects to

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Describe the basic organization of the somatosensory cortex in rats and mice.

Bloom’s Level: 1. Remembering

a. a single neuron in the somatosensory cortex.

b. a single barrel of neurons in the somatosensory cortex.

c. a single cluster of neurons in the somatosensory cortex.

d. a single chain of neurons in the somatosensory cortex.

e. the somatosensory cortex indiscriminately throughout.

Type: multiple choice question

Title: Chapter 23 Question 22

22. Receptive fields of the whiskers on the snout of rats and mice are

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Describe the basic organization of the somatosensory cortex in rats and mice.

Bloom’s Level: 4. Analyzing

a. large and overlapping.

b. small and overlapping.

c. large and nonoverlapping.

d. small and nonoverlapping.

e. absent.

Type: multiple choice question

Title: Chapter 23 Question 23

23. Rats and mice tend to use their whiskers to explore their environment in a way that is analogous, albeit much more extensively, to the way humans use their

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 5. Evaluating

a. arms and legs.

b. hands.

c. fingers.

d. feet.

e. toes.

Type: multiple choice question

Title: Chapter 23 Question 24

24. A rat who has lost a couple of whiskers in an environmental mishap will

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 3. Applying

a. die, because intact whiskers are absolutely essential for survival.

b. recover, because the surviving surrounding whiskers will grow longer to compensate for the lost ones.

c. recover, because the surviving surrounding whiskers will grow thicker wider shafts to compensate for the lost ones.

d. recover, because all the surviving whiskers will become compensate sensory function for that of the lost ones.

e. recover, because the surviving surrounding whiskers’ receptive fields will compensate by taking over the cortical vacancies left by the lost ones.

Type: multiple choice question

Title: Chapter 23 Question 25

25. What is probably the signal that causes the firing of action potentials from the trigeminal nerve when a whisker is deflected?

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 6. Creating

a. Neurotransmitter binding to its GPCR

b. Hormone binding to its GPCR

c. Mechanically gated ion channel

d. Cyclic nucleotide (cAMP)-activated ion channel

e. Mechanical stretch of the skin, resulting in pulling on the whisker shaft

Type: multiple choice question

Title: Chapter 23 Question 26

26. With respect to the cortical layers (I – VI) of the primary somatosensory cortex of rats and mice, barrels are arranged

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 2. Understanding

a. in a parallel fashion.

b. perpendicular to each other.

c. at a 30^⸰ angle.

d. at a 60^⸰ angle.

e. randomly.

Type: multiple choice question

Title: Chapter 23 Question 27

27. Where is the highest concentration of whisker barrels in the mouse primary somatosensory cortex?

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 2. Understanding

a. Layer I

b. Layer II

c. Layer III

d. Layer IV

e. Layer V

Type: multiple choice question

Title: Chapter 23 Question 28

28. A single whisker stimulates a

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 2. Understanding

a. single cortical layer.

b. single cortical barrel.

c. cortical layer and the immediate layers above and below it.

d. cortical barrel and the immediate barrels next to it.

e. single cortical layer and cortical barrel.

Type: multiple choice question

Title: Chapter 23 Question 29

29. The ability of rats to learn among different textures provides evidence that

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Explain how rats use whisker contact to distinguish between different textures.

Bloom’s Level: 2. Understanding

a. rats and mice tend to use their forepaws just as often as they do their whiskers to learn about their environment.

b. rats and mice tend to use their forepaws more often than they use their whiskers to learn about their environment.

c. the whisker-to-brain innervation is highly plastic and adapts to the environmental demands (e.g., different textures).

d. the whisker-to-brain innervation requires that (nearly) all whiskers be intact in order for the rat to learn and successfully navigate his environment.

e. the whisker-to-brain innervation is active only when the whiskers are deflected by some solid texture.

Type: multiple choice question

Title: Chapter 23 Question 30

30. When discriminating among different textures, the amount of neuronal firing by sensory receptor neurons is proportional to the

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Explain how rats use whisker contact to distinguish between different textures.

Bloom’s Level: 3. Applying

a. novelty of the texture object.

b. natural nature of the texture (e.g., dirt vs. an artificial texture, e.g., metal).

c. size of the textured object.

d. shape of the textured object.

e. roughness of the texture object.

Type: multiple choice question

Title: Chapter 23 Question 31

31. A stroke that results death of two-thirds of the neurons of the fingers/hand area of the somatosensory cortex would result in

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the homunculus is and why, like other cortical maps, it is inevitably distorted.

Bloom’s Level: 5. Evaluating

a. permanent inability to feel sensation in the contralateral fingers/hand.

b. permanent inability to feel sensation in the ipsilateral fingers/hand.

c. temporary inability to feel sensation in the contralateral fingers/hand, provided the patient undergoes regular physical therapy of the affected hands and fingers.

d. temporary inability to feel sensation in the ipsilateral fingers/hand, provided the patient undergoes regular physical therapy of the affected hands and fingers.

e. complete paralysis of the contralateral side of the body.

Type: multiple choice question

Title: Chapter 23 Question 32

32. What can be expected to occur in the event of a stroke in an area of the somatosensory cortex if no palliative nor restorative therapies are undertaken (e.g., physical therapy)?

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the homunculus is and why, like other cortical maps, it is inevitably distorted.

Bloom’s Level: 5. Evaluating

a. Those affected neurons will die and glial scarring will gradually fill in the area.

b. Those affected neurons will die, but neighboring neurons will gradually restore function spontaneously.

c. Some of those affected neurons will die, depending on the extent of their damage and glial scarring will gradually fill in the area.

d. Those affected neurons will re-grow and re-establish their original connections.

e. Glial scarring will rapidly develop, thereby inhibiting any attempt of surviving neurons to recuperate.

Type: multiple choice question

Title: Chapter 23 Question 33

33. What is the most likely reason for the somatosensory cortex representing the fingers and hands being so large, but that representing the toes and feet being so small?

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the homunculus is and why, like other cortical maps, it is inevitably distorted.

Bloom’s Level: 5. Evaluating

a. The skin of the feet and toes are much thicker, and therefore, less sensitive than the skin on the palms of your hands and fingers.

b. The feet have evolved to be less sensitive, and therefore, the area of somatosensory cortex that is served by them, has likewise shrunk since humans started wearing shoes.

c. The amount of cortex representing the two distal limbs are actually equivalent, when you consider the part that represents the feet is hidden within the sagittal fissure.

d. The amount of cortex representing the two distal limbs are actually equivalent, when you consider that the homunculus does not only comprised of cortical surface area, but rather, cortical volume, because the cortex is organized into columns.

e. It is impossible to answer this question with significant certainty.

Type: multiple choice question

Title: Chapter 23 Question 34

34. What part of the primary somatosensory cortex receives the densest thalamocortical projections?

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Name two areas on the human body where innervation density and cortical magnification of the skin are grossly distorted.

Bloom’s Level: 3. Applying

a. Fingers and hands

b. Face

c. Trunk

d. Legs

e. Toes and feet

Type: multiple choice question

Title: Chapter 23 Question 35

35. Which of the following body parts has the smallest receptive field?

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Name two areas on the human body where innervation density and cortical magnification of the skin are grossly distorted.

Bloom’s Level: 3. Applying

a. Fingers and hands

b. Face

c. Trunk

d. Legs

e. Toes and feet

Type: multiple choice question

Title: Chapter 23 Question 36

36. The homunculus has a particularly large cortical area devoted to the face, especially the mouth. This is because it receives dense projections from the

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Name two areas on the human body where innervation density and cortical magnification of the skin are grossly distorted.

Bloom’s Level: 3. Applying

a. trigeminal cranial nerve (V),

b. thalamus.

c. internal capsule.

d. parietal cortex.

e. spinal cord.

Type: multiple choice question

Title: Chapter 23 Question 37

37. Which area on the human body is analogous to whiskers on rats and mice in terms of function, innervation density and cortical magnification?

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Name two areas on the human body where innervation density and cortical magnification of the skin are grossly distorted.

Bloom’s Level: 3. Applying

a. Finger tips

b. Hands

c. Lips

d. Eyelids

e. Toes

Type: multiple choice question

Title: Chapter 23 Question 38

38. The main stimulus for the ability to discriminate between coarse and fine surfaces is

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the duplex theory of texture perception is and discuss the evidence that supports it.

Bloom’s Level: 2. Understanding

a. pressure.

b. temperature.

c. vibration.

d. movement.

e. shape.

Type: multiple choice question

Title: Chapter 23 Question 39

39. Perception of rough texture is correlated with firing rate of action potentials by

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the duplex theory of texture perception is and discuss the evidence that supports it.

Bloom’s Level: 2. Understanding

a. slowly adapting Pacinian receptors.

b. quickly adapting Pacinian receptors.

c. Meissner’s receptors.

d. slowly adapting Merkel’s receptors.

e. quickly adapting Merkel’s receptors.

Type: multiple choice question

Title: Chapter 23 Question 40

40. The main difference in protocol in having experimental subjects discriminate between rough and smooth surfaces is that they must

Feedback: Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the duplex theory of texture perception is and discuss the evidence that supports it.

Bloom’s Level: 4. Analyzing

a. be exposed to the rough texture first.

b. be exposed to the smooth texture first.

c. move their finger(s) over the rough texture.

d. move their finger(s) over the smooth texture.

e. wear a glove on the contralateral hand.

Type: essay/short answer question

Title: Chapter 23 Question 41

41. Explain why sitting too long, especially on a hard surface, will eventually be painful.

Feedback: When sitting, the entire weight of the upper body will activate Pacinian corpuscles in the skin of the buttocks and hips. Because compression of these corpuscles results in rapid acclimation, after a prolonged interval, nociceptors and free nerve endings, which are closer to the surface, are stimulated and send pain signals to the primary somatosensory cortex.

Subhead: From Receptors to Cortex

Learning Objective: Differentiate between the two major classes of skin receptors.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 23 Question 42

42. Explain how Pacinian receptors are involved in proprioception and why this is important.

Feedback: Even distribution of body weight along the soles of the feet compresses the deep Pacinian corpuscles, whose lamellae, in turn, compresses the sensory fiber contained in the center. These receptors are rapidly adapting, meaning that the animal quickly grows accustomed to its orientation in 3-dimensional space, which would be advantageous so that the animal can focus its awareness on other environmental features. Their presence in and around the membranous tissues of the joints are also sensitive to vibrations emanating from the ground.

Subhead: From Receptors to Cortex

Learning Objective: Name four different types of receptor complexes and state where they are located.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 23 Question 43

43. Compare a generic hair in the body of a mammal to a highly specialized hair, such as a whisker found in the snout of a rat or mouse.

Feedback: An ordinary hair may be wrapped in free nerve endings that may activate pain receptors when pulled. These nerve endings may also be stimulated in response to cold or activation of the sympathetic nervous system (e.g., arousal), which cause the arrector pili muscle to contract, thereby causing the hair to stand up, called piloerection. In the whisker, however, nerve terminations enter both the superficial and deep portions of the vibrissal nerve, thereby occupying several positions all along the follicle. Such locations cause the whisker to respond to even the slightest stimulus of bending or vibration or even air and water currents. The extent of bending will be related to the nature of the stimulus (e.g., air vs. pushing). Like the generic hair, the whisker is also surrounded by arrector pili muscle, which causes it to bend, but in a restricted sweeping motion.

Subhead: From Receptors to Cortex

Learning Objective: Name four different types of receptor complexes and state where they are located.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 23 Question 44

44. Besides conveying somatosensory impulses of touch, pain, pressure, etc. from the periphery, what do dorsal root ganglion cells also mediate?

Feedback: Reflexes, such as the patellar knee-jerk reflex arc. Upon tapping the patellar tendon, stimulated stretch receptors send impulses through the spinal nerve to the dorsal horn of the spinal cord, where a synapse will be made with an interneuron, which, in turn, synapses with a motor neuron in the ventral horn from where axon will be sent through the same spinal nerve to the effector muscles: the quadriceps muscle to extend and the biceps femoris to flex the lower leg.

Subhead: From Receptors to Cortex

Learning Objective: Describe the three components of receptor neurons that innervate the skin of the hands, feet, arms, legs, and trunk.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 23 Question 45

45. If electrical circuits were embedded in the skin of an artificial limb to help amputees feel and manipulate, what must happen for this to be successful?

Feedback: Successful joining of the severed nerve must be made with the artificial limb.

Subhead: From Receptors to Cortex

Learning Objective: Define microneurography and discuss what advantages it offers over animal investigations.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 23 Question 46

46. How could the mapping of human sensory receptive fields be useful in diagnosing spinal cord injury?

Feedback: By lightly pricking a body part with a sharp object and then observing the patient’s response (or lack of it), a physician can determine which segment of the spinal cord has been damaged.

Subhead: From Receptors to Cortex

Learning Objective: Define microneurography and discuss what advantages it offers over animal investigations.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 23 Question 47

47. Explain how opiate receptors can bind both endorphins and opiates, such as morphine.

Feedback: Receptors are highly dynamic macromolecules, which can alter their overall structure upon binding their respective ligand. Endorphins are small peptides and bear no resemblance to morphine, a phenanthrene. To be able to accommodate both kinds of molecules that differ so much in both shape and size, the active site must be undergo drastic conformational changes.

Subhead: From Receptors to Cortex

Learning Objective: Describe the two systems involved in processing pain signals.

Bloom’s Level: 5. Evaluating

Type: essay/short answer question

Title: Chapter 23 Question 48

48. In pain transmission, how does the medial system affect the lateral system?

Feedback: The lateral system is objective, meaning that pain signals (action potentials) will be transmitted uninterrupted to the somatosensory cortex. However, the subjective nature of the medial stream can modulate the pain that is ultimately felt. Subjective expectations, prior experiences, personality, and current emotional state of mind all affect how much pain is perceived. In some cases, these personality traits can magnify the pain, while in others, pain is perceived to be less than it objectively should be.

Subhead: From Receptors to Cortex

Learning Objective: Explain how placebo treatment works.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 23 Question 49

49. Cite a piece of evidence that shows that rats trust their whiskers more than their eyes to navigate a novel environment.

Feedback: Being small relatively defenseless animals, they favor dark places in which they can hide. In one experiment, rats were supposed to step down from a brightly lit platform to a dark area. En route to the dark area was an invisible (glass) platform. Despite the motivation to hide in the small dark space and the fact that they cannot see any platform, rats will step onto the invisible platform only if they can feel it with their whiskers.

Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Describe the basic organization of the somatosensory cortex in rats and mice.

Bloom’s Level: 1. Remembering

Type: essay/short answer question

Title: Chapter 23 Question 50

50. Outline the pathway that input takes from whisker to cortex in rats and mice.

Feedback: Movement of a whisker sends impulses to barralette in the brainstem trigeminal nucleus to a corresponding barraloid in the thalamic ventromedial posterior nucleus to a corresponding cortical barraloid.

Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 23 Question 51

51. Discuss the neurons that comprise the barrel cortex in rats and mice.

Feedback: The barrel cortex is composed of different kinds of neurons, but with one property in common: the ability to respond to whisker movement. Neurons in Layer 4 barrel cortex respond exclusively or most strongly to the dynamics of one whisker: its degree of angular displacement, bending and rate of such displacement by firing action potentials proportionately. These neurons are also directionally selective, firing only when their whisker is bent in a certain direction. When the whisker is bent, some neurons will fire continuously for the duration of the whisker being bent; others will fire only initially in response to the whisker bending, but will cease firing and then return to baseline levels of activity. Neurons in other layers (besides layer 4) are less committed to just one whisker and can distribute their responses to the movements of multiple whiskers.

Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Discuss how the topographical map of cortical columns serves to organize the storage of sensory experiences in rats and mice.

Bloom’s Level: 2. Understanding

Type: essay/short answer question

Title: Chapter 23 Question 52

52. After a rat runs its whiskers over a novel surface a number of times, it will decide what to do about it. For example, if a narrow pipe, the kind found in the plumbing of an old building, the rat will decide whether to enter it. How does the rat arrive at this decision?

Feedback: Such a pipe will have different textures of rough and smooth, depending on how old, rusty, and dirty it is. The ratio of rough-to-smooth textures the rat encounters and evaluates will be stored in the barrel cortex. A high ratio indicates more rough than smooth surfaces and, therefore, higher firing rate from the whiskers to the barrel cortex. Peripherally, a rough texture will cause the whisker to momentarily stick, resist, and then release or slip; this process will be repeated as each whisker encounters the same or similar imperfections on the surface that qualifies it as rough. This amount of sticking and slipping will be transmitted to the barreloid in the language of action potential firing.

Subhead: Somatosensory System Organization and Texture Sensation in Rats and Mice

Learning Objective: Explain how rats use whisker contact to distinguish between different textures.

Bloom’s Level: 3. Applying

Type: essay/short answer question

Title: Chapter 23 Question 53

53. Would you expect the homunculus for touch to be different from that for pain? Why or why not?

Feedback: Touch and pain are two different, but inseparable responses. Which one is manifest depends on the degree of the stimulus. The back of the hand can be gently pressed or poked with a sharp object, Both stimulations will terminate in the same place on the somatosensory cortex. Both stimulations may also elicit a subjective interpretation, much of which depends on the intent of each stimulus.

Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the homunculus is and why, like other cortical maps, it is inevitably distorted.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 23 Question 54

54. You are measuring resolution on your lab partner’s body (resolution is the ability to discriminate one point from two closely-spaced points when poked with a compass on the skin, without the subject looking, of course). Suppose the two compass points are 5 mm apart. Why does your partner perceive this to be one point when poked on his back, but perceives it to be two points when poked on his upper lip?

Feedback: The lips and face are much more sensitive and can therefore, resolve two closely spaced points, because of the small receptive fields. The trunk, however, has much larger receptive fields and therefore, the compass points would have to be farther apart than 5 mm before the subject perceives two points; at this distance of 5 mm, on the trunk, the subject perceives only one point.

Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Name two areas on the human body where innervation density and cortical magnification of the skin are grossly distorted.

Bloom’s Level: 4. Analyzing

Type: essay/short answer question

Title: Chapter 23 Question 55

55. Explain why it is advantageous to activate slowly adapting receptors when reading Braille.

Feedback: To be able to discriminate among the vastly different arrangements of dots and continue reading efficiently, it is important that the reader not (quickly) grow accustomed to their different patterns.

Subhead: Somatosensory System Organization and Texture Sensation in Primates

Learning Objective: Explain what the duplex theory of texture perception is and discuss the evidence that supports it.

Bloom’s Level: 3. Applying