Chapter 14 The Cutaneous Senses Answer Key

Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses Multiple Choice 1. The somatosensory system comprises _____. a. the cutaneous sensory system only b. cutaneous sensations and proprioception only c. cutaneous sensations and kinesthesis only d. cutaneous sensations, proprioception, and kinesthesis ANSWER: d 2. The outer layer of the skin is composed of _____. a. a lipid layer b. Meissner corpuscles c. Pacinian corpuscles d. dead skin cells ANSWER: d 3. The _____ are located near the border of the epidermis and surface of the skin, and are associated with sensing fine details. a. Pacinian corpuscle b. Meissner corpuscles c. Ruffini cylinders d. Merkel receptors ANSWER: d 4. Which mechanoreceptor is located deeper in the skin and responds continuously to stimulation and is associated with perceiving stretching of the skin? a. Pacinian corpuscles b. Ruffini cylinders c. Merkel receptors d. Meissner corpuscles ANSWER: b 5. The _____ are responsible for the perception of rapid vibrations, such as you would experience when using a hand-held massager. a. Pacinian corpuscles b. Meissner corpuscles c. Ruffini cylinders d. Merkel receptors ANSWER: a Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses 6. The Meissner corpuscle is associated with _____. a. sensing vibrations b. sensing fine texture c. controlling handgrip d. sensing fine details ANSWER: c 7. The nerve fibers in the spinal cord go in _____. a. the medial lemniscal pathway only b. the spinothalamic pathway only c. the geniculostriate pathway only d. both the medial lemniscal pathway and the spinothalamic pathway ANSWER: d 8. Ian Waterman was able to sense pain and temperature because his _____ pathway was intact, but could not feel touch and limb position because of damage to his _____ pathway. a. lemniscal; spinothalamic b. spinothalamic; lemniscal c. homuncular; lemniscal d. spinothermal; spinothalamic ANSWER: b 9. The fibers from the medial lemniscal pathway and the spinothalamic pathway go to the _____. a. lateral geniculate nucleus b. medial geniculate nucleus c. ventrolateral nucleus d. hypothalamus ANSWER: c 10. Penfield mapped locations of body parts on area S1 by _____. a. using fMRIs in humans b. lesioning S1 areas in the monkey c. using somatosensory-evoked potentials in monkeys d. stimulating S1 areas in humans, and asking where they felt body sensations ANSWER: d 11. The mapping of the body on the somatosensory cortex can be represented as a(n) _____. a. homunculus b. anosmia c. epidermis d. pachyderm Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses ANSWER: a 12. The area on S1 associated with the thumb is as large as the area for the forearm. This is an example of _____. a. sensory substitution b. Braille projection c. cortical magnification d. the analgesic inversion principle ANSWER: c 13. Which of the following is true regarding body mapping in the somatosensory cortex? a. Body maps only appear in S1. b. Body map regions are proportionate to the actual size of the body parts. c. Body maps appear in both the frontal and parietal lobes. d. Body maps appear in S1 and S2. ANSWER: d 14. Experience-dependent plasticity has been found to occur for _____. a. the somatosensory system only b. the auditory system only c. only the auditory and somatosensory systems d. the somatosensory, auditory, and visual systems ANSWER: d 15. Jan is a right-handed violin player – she bows with her right hand and fingers the strings with her left. The cortical representation for the fingers on her left hand is _____. a. equal to the area for the fingers on her right hand b. equal to the area for the fingers on the left hand of a non-musician c. larger than the area for the fingers on the left hand of a non-musician d. smaller than the area for the fingers on the left hand of a nonmusician ANSWER: c 16. Which type of acuity is measured by pressing a grooved stimulus onto the skin and asking the person to indicate the orientation? a. grating b. letter c. two-point d. Braille simulated ANSWER: a 17. Which body part is the most sensitive to detail? Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses a. fingertips b. palms c. forehead d. upper arm ANSWER: a 18. The density of the _____ on the fingertips than on the palms. a. Merkel receptors is higher b. Krausse end bulbs is higher c. Merkel receptors is lower d. Pacinian corpuscles is lower ANSWER: a 19. The receptive fields of cortical S1 neurons are _____. a. larger for the fingers than for the forearm b. larger for the fingers than for the hand c. smaller for the fingers than the forearm d. the same size for the fingers as for the hand ANSWER: c 20. The mechanoreceptors primarily responsible for feeling the vibrations from an electric toothbrush are _____ because these receptors contain an “onion-like” series of layers. a. Pacinian corpuscles b. Merkel receptors c. Ruffini cylinders d. Meissner corpuscles ANSWER: a 21. Moving your finger across a textured surface can produce vibrations that are interpreted as texture. These vibrations are defined as _____. a. parietal cues b. temporal cues c. spatial cues d. olfactory cues ANSWER: b 22. The duplex theory of texture perception refers to the importance of _____. a. temporal cues and spatial cues b. parietal cues and occipital cues Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses c. spatial cues and occipital cues d. temporal cues and parietal cues ANSWER: a 23. The demonstration in which you perceived the texture of a surface using your pen or another “tool” showed _____. a. it is difficult to determine texture without directly touching the surface b. passive touch is more important than active touch in texture perception c. texture gradients are more important for vision than cutaneous senses d. that you can use vibrations to perceive the texture of the surface ANSWER: d 24. In most of our daily experience of touch, we are using _____. a. passive touch b. active touch c. two-point touch d. two-hand touch ANSWER: b 25. When you try to identify a three-dimensional object by touch alone and are allowed to have control over your hand and finger movements, you are using _____. a. passive touch b. haptic perception c. azimuth perception d. magnification touch ANSWER: b 26. People use mainly _____ to judge texture. a. enclosure and lateral motion b. pressure and enclosure c. contour following and enclosure d. lateral motion and contour following ANSWER: d 27. Bobby is asked to use haptic perception to identify a soccer ball. She will most likely use the exploratory procedure(s) of _____ to identify the soccer ball’s exact shape. a. lateral motion and pressure b. pressure only c. enclosure and contour following d. passive motion and lateral motion Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses ANSWER: c 28. Passive touch is to experiencing _____ as active touch is to experiencing _____. a. the object; stimulation of the skin b. intermittent stimulation; continuous stimulation c. continuous stimulation; intermittent stimulation d. stimulation of the skin; the object ANSWER: d 29. Neurons in the ventral posterior nucleus in the thalamus have _____. a. center-surround receptive fields b. ill-defined receptive fields c. no receptive fields d. grating-like receptive fields ANSWER: a 30. As we move from mechanoreceptor fibers in the fingers toward the brain, we see that neurons become _____. a. less specialized b. more inhibitory c. less inhibitory d. more specialized ANSWER: d 31. Neuropathic pain is to _____ as inflammatory pain is to _____. a. tumor cells; phantom limb syndrome b. tumor cells; carpal tunnel syndrome c. carpal tunnel syndrome; azimuth burn d. carpal tunnel syndrome; tumor cells ANSWER: d 32. The phenomenon of “phantom limb” is difficult to explain using the _____ of pain. a. direct pathway model b. gate control model c. nocioceptor model d. neuropathic model ANSWER: a 33. According to the gate control theory of pain, the _____ opens the pain gate by sending excitation to _____. a. mechanoreceptors; transmission cells Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses b. SG+; nocioceptors c. SG-; mechanoreceptors d. nociceptors; transmission cells ANSWER: d 34. Pokorny, a burn victim, reduced perceived pain by _____. a. viewing photographs of other burn victims b. microstimulation to the nocioreceptors in the forearm c. having a discussion of the placebo effect with his doctor d. playing a virtual-reality “game” during treatment ANSWER: d 35. Lucy, a heterosexual female, would be able to keep her hand immersed in cold water longer if she was _____. a. looking at pictures of a refrigerator b. looking at pictures of accidents c. looking a pictures of attractive males d. visualizing images of war ANSWER: c 36. Research by Derbyshire et al. (2003) Hofbauer et al. (2001) showed that hypnotic suggestion _____. a. causes changes in somatosensory cortex for changes in affective component of pain b. can cause changes in anterior cingulate cortex for changes in sensory component of pain c. causes changes in somatosensory cortex for changes in sensory component of pain d. can cause changes in somatosensory cortex for changes in emotional component of pain ANSWER: c 37. In the perception of pain, the _____ communicates directly with the amygdala, insula and ACC. a. PFC b. S2 c. S1 d. thalamu s ANSWER: d 38. The sensory component of pain is to _____ as the emotional component of pain is to _____. a. throbbing; dull b. annoying; sickening c. frightful; prickly d. throbbing; annoying Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses ANSWER: d 39. The phrase “multimodal nature of pain” refers to _____. a. pain that occurs from different sources b. pain that is tolerable and pain that is intolerable c. the sensory and emotional components of pain d. real and imagined sources of pain ANSWER: c 40. The subjective intensity of pain is to _____ as the unpleasantness of pain is to _____. a. somatosensory cortex; Area S2 b. real pain; phantom pain c. the ACC; Area S2 d. somatosensory cortex; the ACC ANSWER: d 41. Based on the finding that _____, it is believed that endorphins are linked to pain relief. a. naloxone injections increase the analgesic effect of endorphins b. naloxone injections decrease the analgesic effect of endorphins and placebos c. naloxone injections increase the analgesic effects of placebos d. placebo injections increase the analgesic effects of endorphins ANSWER: b 42. Endorphins are _____. a. morphine-like substances found in the body b. receptors that are stimulated by extreme temperature on the skin c. the active agent in placebos d. able to overcome only very mild, tolerable pain ANSWER: a 43. Stroking a participants’ leg leads to increased activation in S2 and S2 activity also increased when participants _____. a. saw a video of the same leg moving around in isolation b. saw a video depicting someone stroking an office supply binder c. thought about an object moving toward someone’s leg d. thought about lifting the same leg and moving it around ANSWER: b Essay 44. Name and discuss the differences between the four types of mechanoreceptors. ANSWERMany of the tactile perceptions that we feel from stimulation of the skin can be traced : to mechanoreceptors that are located in the epidermis and the dermis. Two Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses mechanoreceptors, the Merkel receptor and the Meissner corpuscle, are located close to the surface of the skin, near the epidermis. Because they are located close to the surface, these receptors have small receptive fields; a cutaneous receptive field is the area of skin which, when stimulated, influences the firing of the neuron. The two other mechanoreceptors, the Ruffini cylinder (SA2 fiber) and the Pacinian corpuscle (RA2 or PC fiber), are located deeper in the skin, so they have larger receptive fields. The Ruffini cylinder responds continuously to stimulation, and the Pacinian corpuscle responds when the stimulus is applied and removed. The Ruffini cylinder is associated with perceiving stretching of the skin, the Pacinian corpuscle with sensing rapid vibrations and fine texture. 45. Discuss how cortical magnification and plasticity are related to the cortical mapping of area S1. ANSWERThe homunculus shows that adjacent areas of the skin project to adjacent areas in the : brain, and that some areas on the skin are represented by a disproportionately large area of the brain. The area devoted to the thumb, for example, is as large as the area devoted to the entire forearm. This result is analogous to the magnification factor in vision, in which receptors in the fovea, which are responsible for perceiving visual details, are allotted a disproportionate area on the visual cortex. Similarly, parts of the body such as the fingers, which are used to detect details through the sense of touch, are allotted a disproportionate area on the somatosensory cortex (Duncan & Boynton, 2007). A similar body map also occurs in the secondary somatosensory cortex (S2). One of the basic principles of cortical organization is that the cortical representation of a particular function can become larger if that function is used often. Most of the early experiments that demonstrated experience-dependent plasticity were carried out in the somatosensory system. In one of these early experiments, William Jenkins and Michael Merzenich (1987) measured the cortical areas devoted to each of a monkey’s fingers and then trained monkeys to complete a task that involved the extensive use of a particular location on one fingertip. When they compared the cortical maps of the fingertip measured just before the training to the map measured after 3 months of training, they found that the area representing the stimulated fingertip was greatly expanded after the training. Thus, the cortical area representing part of the fingertip, which is large to begin with, became even larger when the area received a large amount of stimulation. In most animal experiments, like the one we just described, the effect of plasticity is determined by measuring how special training affects the brain. An experiment that measured this effect in humans determined how training affected the brains of musicians. Consider, for example, players of stringed instruments. A right-handed violin player bows with the right hand and uses the fingers of his or her left hand to finger the strings. One result of this tactile experience is that these musicians have a greater than normal cortical representation for the fingers of their left hand (Elbert et al., 1995). Just as in the monkeys, plasticity created more cortical area for parts of the body that were used more. What this plasticity means is that while we can specify the general area of the cortex that represents a particular part of the body, the exact size of the area representing each part of the body is not totally fixed (Pascual-Leone et al., 2005). 46. What is the duplex theory of texture perception? Describe research that supports this theory. Name : Clas s: Chapter 14: The Cutaneous Senses ANSWERIn 1925, David Katz proposed what is now called the duplex theory of texture : perception, which states that our perception of texture depends on both spatial cues and temporal cues (Hollins & Risner, 2000; Katz, 1925/1989). Spatial cues are provided by relatively large surface elements, such as bumps and grooves, that can be felt both when the skin moves across the surface elements and when it is pressed onto the elements. These cues result in feeling different shapes, sizes, and distributions of these surface elements. An example of the use of spatial cues is perceiving a coarse texture such as Braille dots or the texture you feel when you touch the teeth of a comb. Temporal cues occur when the skin moves across a textured surface like fine sandpaper. This type of cue provides information in the form of vibrations that occur as a result of the movement over the surface. Temporal cues are responsible for our perception of fine texture that cannot be detected unless the fingers are moving across the surface. Although Katz proposed that texture perception is determined by both spatial and temporal cues, research on texture perception has, until recently, focused on spatial cues. However, experiments by Mark Hollins and coworkers (2000, 2001, 2002) show that temporal cues are responsible for our perception of fine textures. Hollins and Ryan Risner (2000) presented evidence for the role of temporal cues by showing that when subjects touched surfaces without moving their fingers and judged “roughness” using the procedure of magnitude estimation, they sensed little difference between two fine textures (particle sizes of 10 μm and 100 μm). However, when subjects were allowed to move their fingers across the surface, they could detect the difference between the fine textures. Thus, movement, which generates vibration as the skin scans a surface, makes it possible to sense the roughness of fine surfaces. 47. Explain how haptic exploration is used to identify objects. ANSWERHaptic perception provides a particularly good example of a situation in which a : number of different systems are interacting with each other. As you manipulated the objects in the first part of the demonstration above, you were using three distinct systems to arrive at your goal of identifying the objects: (1) the sensory system, which was involved in detecting cutaneous sensations such as touch, temperature, and texture and the movements and positions of your fingers and hands; (2) the motor system, which was involved in moving your fingers and hands; and (3) the cognitive system, which was involved in thinking about the information provided by the sensory and motor systems. Haptic perception is an extremely complex process because the sensory, motor, and cognitive systems must all work together. For example, the motor system’s control of finger and hand movements is guided by cutaneous feelings in the fingers and the hands, by your sense of the positions of the fingers and hands, and by thought processes that determine what information is needed about the object in order to identify it. 48. Describe the basic principles of the gate-control model of pain. ANSWERThe gate control model begins with the idea that pain signals enter the spinal cord from : the body and are then transmitted from the spinal cord to the brain. In addition, the model proposes that there are additional pathways that influence the signals sent from the spinal cord to the brain. The central idea behind the theory is that signals from these additional pathways can act to open or close a gate, located in the spinal cord, which determines the strength of the signal leaving the spinal cord. Dat e: Name : Clas s: Chapter 14: The Cutaneous Senses We can understand how this circuit functions by considering how input to the gate control system occurs along three pathways: Nociceptors. Fibers from nociceptors activate a circuit consisting entirely of excitatory synapses, and therefore send excitatory signals to the transmission cells. Excitatory signals from the (+) neurons in the dorsal horn “open the gate” and increase the firing of the transmission cells. Increased activity in the transmission cells results in more pain. Mechanoreceptors. Fibers from mechanoreceptors carry information about nonpainful tactile stimulation. An example of this type of stimulus would be signals sent from rubbing the skin. When activity in the mechanoreceptors reaches the (–) neurons in the dorsal horn, inhibitory signals sent to the transmission cells “close the gate” and decrease the firing of the transmission cells. This decrease in firing decreases the intensity of pain Central control. These fibers, which contain information related to cognitive functions such as expectation, attention, and distraction, carry signals down from the cortex. As with the mechanoreceptors, activity coming down from the brain also closes the gate, decreases transmission cell activity, and decreases pain. Since the introduction of the gate control model in 1965, researchers have determined that the neural circuits that control pain are much more complex than what was proposed in the original model (Perl & Kruger, 1996; Sufka & Price, 2002). Nonetheless, the idea proposed by the model - that the perception of pain is determined by a balance between input from nociceptors in the skin and nonnociceptive activity from the skin and the brain - stimulated research that provided a great deal of additional evidence for the idea that the perception of pain is influenced by more than just stimulation of the skin (Fields & Basbaum, 1999; Sufka & Price, 2002; Turk & Flor, 1999; Weissberg, 1999). 49. Discuss at least three ways in which cognitive factors can influence pain perception. ANSWERModern research has shown that pain can be influenced by what a person expects, how : the person directs his or her attention, the type of distracting stimuli that are presented, and suggestions made under hypnosis (Rainville et al., 1999; Wiech et al., 2008). In a hospital study in which surgical patients were told what to expect and were instructed to relax to alleviate their pain, the patients requested fewer painkillers following surgery and were sent home 2.7 days earlier than patients who were not provided with this information (Egbert et al., 1964). Studies have also shown that a significant proportion of patients with pathological pain get relief from taking a placebo, a pill that they believe contains painkillers but that, in fact, contains no active ingredients (Finniss & Benedetti, 2005; Weisenberg, 1977). This decrease in pain from a substance that has no pharmacological effect is called the placebo effect. The key to the placebo effect is that the patient believes that the substance is an effective therapy. This belief leads the patient to expect a reduction in pain, and this reduction does, in fact, occur. Many experiments have shown that expectation is one of the more powerful determinants of the placebo effect (Colloca & Benedetti, 2005). Examples of the effect of attention on pain were noted in the 1960s by Melzack & Wall (1965) as they were developing their gate control theory of pain. One conclusion that Dat e: Name : Clas s: Dat e: Chapter 14: The Cutaneous Senses we might draw is that one way to decrease pain would be to distract a person’s attention from the source of the pain. This technique has been used in hospitals using virtual reality techniques as a tool to distract attention from a painful stimulus. Consider, for example, the case of James Pokorny, who received third-degree burns over 42 percent of his body when the fuel tank of the car he was repairing exploded. While having his bandages changed at the University of Washington Burn Center, he wore a black plastic helmet with a computer monitor inside, on which he saw a virtual world of multicolored three-dimensional graphics. This world placed him in a virtual kitchen that contained a virtual spider, and he was able to chase the spider into the sink so he could grind it up with a virtual garbage disposal (Robbins, 2000). The point of this “game” was to reduce Pokorny’s pain by shifting his attention from the bandages to the virtual reality world. Pokorny reports that “you’re concentrating on different things, rather than your pain. The pain level went down significantly.” Studies of other patients indicate that burn patients using this virtual reality technique experienced much less pain when their bandages were being changed than patients in a control group who were distracted by playing video games (Hoffman et al., 2000) or who were not distracted at all (Hoffman et al., 2008; also see Buhle et al., 2012). A great deal of evidence shows that pain perception can be influenced by a person’s emotional state, with many experiments showing that positive emotions are associated with decreased pain (Bushnell et al., 2013). Two ways this has been demonstrated is by having people look at pictures and having them listen to music. 50. Discuss research by Singer et al. (2004) that demonstrates how social situations can affect pain perception. ANSWERTania Singer and coworkers (2004) demonstrated the connection between brain : responses to pain and empathy by bringing romantically involved couples into the laboratory and having the woman, whose brain activity was being measured by an fMRI scanner, either receive shocks herself or watch her male partner receive shocks. The results show that a number of brain areas were activated when the woman received the shocks, and that some of the same areas were activated when she watched her partner receive shocks. The main two areas activated in common were the anterior cingulate cortex (ACC) and the anterior insula (AI), both of which are associated with the affective component of pain. To show that the brain activity caused by watching their partner was related to empathy, Singer had the women fill out “empathy scales” designed to measure their tendency to empathize with others. As predicted, women with higher empathy scores showed higher activation of their ACC.