Module 2 Lecture 1: Touch and Proprioception and Lecture 2: Pain

1. Which pathway represents a route that pain information could take in the nervous system?
a. Free nerve ending nociceptor, unmyelinated C fiber axon, spinal cord
b. Free nerve ending nociceptor, myelinated C fiber axon, spinal cord
c. Unspecialized, unmyelinated A axon, spinal cord
d. Specialized pain receptor, partially myelinated A axon, brainstem
e. Mechanoreceptor, myelinated axons, cranial nerve, spinal cord
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1. Which pathway represents a route that pain information could take in the nervous system?
a. Free nerve ending nociceptor, unmyelinated C fiber axon, spinal cord
b. Free nerve ending nociceptor, myelinated C fiber axon, spinal cord
c. Unspecialized, unmyelinated A axon, spinal cord
d. Specialized pain receptor, partially myelinated A axon, brainstem
e. Mechanoreceptor, myelinated axons, cranial nerve, spinal cord
Answer: a
2. What do nociceptor neurons and non-nociceptor somatosensory neurons have in common?
a. Unspecialized nerve endings
b. Specialized nerve endings
c. Conduction velocity
d. Highly-myelinated axons
e. Cell body located in the dorsal root ganglia
Answer: e
3. Refer to the graph.



Which conclusion about the neuronal basis of pain is consistent with the graph?
a. Stimuli of certain temperatures can activate nociceptors but not thermoreceptors.
b. These nociceptors respond only to stimuli that are sufficiently warm (approximately 43°C or above).
c. There is a linear relationship between thermoreceptor response and temperature of the stimulus.
d. The nociceptors and thermoreceptors respond to a thermal stimulus by decreasing the frequency of action potentials
e. Any thermal stimulus can activate both the nociceptors and the thermoreceptors.
Answer: b
4. Which fibers conduct the sensation of first pain?
a. Unmyelinated C
b. Myelinated Aδ
c. Myelinated Ia
d. Unmyelinated II
e. Myelinated Aβ
Answer: b
5. Which sensation would an individual with anesthetized C fibers report when exposed to intense heat?
a. Sharp pain followed by a dull burning
b. Sharp pain only
c. Dull burning only
d. Tingling
e. No sensation
Answer: b
6. Which channel is responsible for transmitting information about chemical irritants, such as components of cigarette smoke, in the environment?
a. TRPV1
b. TRPA1
c. TRPV4
d. Piezo 2
e. ASIC3
Answer: b
7. ASIC channels are involved in generating the sensation of pain associated with heart attack because, during heart attack,
a. pH of the tissue increases, which activates the channels.
b. pH of the tissue decreases, which activates the channels.
c. heart tissue undergoes necrosis, the products of which activate the channels.
d. heart muscle contracts, and this mechanical force activates the channels.
e. capsaicin produced in the heart muscle activates the channels.
Answer: b
8. What makes neurons of Rexed's lamina V a likely substrate for referred pain?
a. They receive nociceptive information.
b. They receive somatosensory information.
c. They receive converging information from somatosensory and nociceptive axons.
d. They project directly to cortical structures.
e. They receive descending inputs from the locus coeruleus.
Answer: c
9. Which deficit would a lesion restricted to the right side of the spinal cord produce?
a. Mechanosensory deficit on the right side of the body only
b. Mechanosensory deficit on the left side of the body only
c. Pain deficit on the right side of the body only
d. Pain deficit on the left side and mechanosensory deficit on the right side of the body
e. Pain deficit on the right side and mechanosensory deficit on the left side of the body
Answer: d
10. Which structure contributes to the sensory-discriminative aspect of pain?
a. Anterior cingulate cortex
b. Ventral posterior medial nucleus of thalamus
c. Ventral posterior lateral nucleus of thalamus
d. Amygdala
e. Ventral posterior medial and lateral nuclei of the thalamus
Answer: e
11. The small receptive fields of SI nociceptor neurons make possible the a. perception of affective-motivational aspects of pain. b. perception of extreme pain. c. perception of weak pain. d. precise localization of pain. e. All of the aboveAnswer: d12. Disruption of the _______ system prevents the transmission of _______ information. a. dorsal column-mediated lemniscal; visceral pain b. anterolateral; vibration c. dorsal column-mediated lemniscal; temperature d. anterolateral; visceral pain e. anterolateral; mechanosensoryAnswer: a13. Colon cancer pain has been shown to be relieved by disruption of the visceral pain pathway at the level of the a. spinal cord near the midline at the sacral level. b. spinal cord near the midline at the thoracic level. c. ventral horn ipsilateral to the site of pain at the thoracic level. d. dorsal horn contralateral to the site of pain at the thoracic level. e. insular cortex ipsilateral to the site of pain.Answer: b14. Where are the bodies of first-order neurons that conduct pain and thermal information from the face located? a. Pars interpolaris b. Ventral posterior medial nucleus c. Brainstem d. Thalamus e. Trigeminal ganglia and ganglia of cranial nerves VII, IX, and XAnswer: e15. Which perception is an example of hyperalgesia? a. Pain following a small paper cut b. Pain following sunburn c. Sensitivity to innocuous stimulus like the sound of scratching a plate with a fork d. Increased sensitivity to light during a migraine episode e. Increased sensitivity to temperature after sunburnAnswer: e16. Which mechanism contributes to peripheral sensitization following tissue damage? a. Release of peptides and neurotransmitters from nociceptors b. Migration of immune cells to the site of damage c. Release of proinflammatory substances by the non-neuronal cells d. Potentiation of nociceptors by soluble proinflammatory substances e. All of the aboveAnswer: e17. Is it possible for an innocuous stimulus, such as touch, to evoke a sensation of pain? a. No, because the different types of information travel through separate pathways. b. No, because an innocuous stimulus is not strong enough to evoke pain sensation. c. Yes, because pain and touch information share a common pathway. d. Yes, it occurs by means of central sensitization. e. Yes, it occurs by means of peripheral sensitization.Answer: d18. What is the basis of the windup form of central sensitization? a. Summation of slow postsynaptic potentials in the dorsal horn neurons b. Elevation of intracellular Ca2+ levels in the dorsal horn neurons c. Elevation of intracellular Cl- levels in the dorsal horn neurons d. Increase in transcription of the COX-2 enzyme e. Increase in production of chemokines by astrocytesAnswer: a19. Phantom pain is an example of a. allodynia. b. neuropathic pain. c. peripheral sensitization. d. potentiation. e. hallucination.Answer: b20. Refer to the figure. Touching which body part, on a person who is missing his right hand, is most likely to evoke a sensation of being touched on his right fingers? a. Right eye b. Scalp c. Right shoulder d. Right leg e. Left jawAnswer: c21. Which statement about placebos is most accurate? a. Studies of the placebo effect prove that some people are imagining they feel pain. b. The use of placebos is a relatively new strategy for treating pain. c. Placebos relieve pain in some people by stimulating endogenous opioid receptors. d. In a study of patients with postoperative wounds, the placebo effect was shown to be ineffective in 75% of subjects given sterile saline as the placebo. e. None of the aboveAnswer: c22. Which center has the highest order within the system that modulates the transmission of ascending pain signals? a. Raphe nuclei b. Locus coeruleus c. Parabrachial nucleus d. Medullary reticular formation e. Midbrain periaqueductal gray matterAnswer: e23. Which statement correctly summarizes the gate theory of pain? a. Flow of ascending pain information is modified by stimulation of low-threshold mechanoreceptors. b. Flow of ascending pain information is modified by stimuli from cortical centers. c. Flow of ascending pain information is modified by stimuli from brainstem centers. d. Descending inputs from pain centers indirectly modify the activity of dorsal horn projection neurons by acting on local circuit neurons. e. Descending inputs from pain centers directly modify the activity of dorsal horn projection neurons.Answer: a24. Receptors to which class of molecules are also found on microglia? a. Exogenous opiates b. Enkephalines c. Endorphins d. Dynorphins e. EndocannabinoidsAnswer: e25. In which region of the brain can all three endogenous opioid peptides be found? a. Rostral ventral medulla b. Dorsal horns of the spinal cord c. Periaqueductal gray matter d. Amygdala e. InsulaAnswer: c1. What is the evidence that nociception is mediated by specific nociceptors rather than by strong stimulation of somatosensory receptors or non-nociceptive thermoreceptors?Answer: Transcutaneous nerve recording experiments have revealed that nociceptors and thermoreceptors respond differently to the same stimulus. Thermoreceptors reach their maximum firing rate at a temperature below the pain threshold and maintain that rate even at increasing levels of heat stimulation, whereas nociceptive thermoreceptors begin firing at a higher stimulus intensity and increase their firing rate as the stimulus intensity increases.8. The placebo effect on pain can be blocked by naloxone. What does this observation reveal about the placebo effect?Answer: Naloxone is an opioid receptor antagonist. Since naloxone can block the pain-relieving effect of a placebo, the placebo effect appears to exert its effect by activating endogenous opioid receptors.3. Which statement about TRP receptors is false? a. TRP channels are very specialized and found only in the pain system. b. TRP channels were discovered in studies of Drosophila phototransduction. c. TRPV1 receptors are sensitive to capsaicin and moderate heat. d. TRPV1 receptors might be activated by endogenous compounds that are structurally related to capsaicin. e. TRP channels structurally resemble voltage-gated potassium channels.Answer: a10. Which statement does not express one of the observations that contributed to the concept of a dorsal column pain pathway? a. Spinal afferents project to the spinal intermediate gray matter. b. Intermediate gray axons project through the dorsal columns. c. Ventral posterior lateral nucleus and gracile nucleus neurons respond to noxious stimuli. d. Ventral posterior lateral nucleus and gracile nucleus pain responses are lost after a dorsal column lesion. e. Tactile sensations, but not pain sensations, are lost after the infusion of nociceptive inhibitors into the spinal intermediate gray region.Answer: e14. Pruriceptors are a. signals emanating from the central autonomic nuclei. b. receptors that convey the affective nature of unpleasant or noxious stimuli. c. subsets of C fibers that are activated by itch-inducing stimuli. d. receptors concerned with the physiological states of the body. e. receptors involved in local motor pattern generation within visceral organs.Answer: c16. Which statement about phantom limbs and phantom limb pain is false? a. Phantom limb sensation occurs in only a very small fraction of amputees, since illusory phantom limbs are rare. b. Phantom limb sensation and pain can occur transiently after local nerve block. c. Phantom limb sensation and pain are not relieved by ablations of the spinothalamic tract or sensory cortex. d. Phantom limb sensations can occur in children born without limbs. e. Mirror box therapy can offer relief for some individuals that experience phantom limb pain.Answer: a18. Which statement regarding the descending control of pain is false? a. Electrical and pharmacological stimulation of certain midbrain regions can alleviate pain. b. Insertion of acupuncture needles into the periaqueductal gray produces the same effect as electrically stimulating it. c. The cholinergic, dopaminergic, histaminergic, serotonergic, and noradrenergic systems all contribute to descending control of pain. d. Descending pathways can exert both excitatory and inhibitory influences on the activity of dorsal horn neurons. e. Descending control is mediated by synaptic contacts onto dorsal horn projection neurons, nociceptive afferents, excitatory and inhibitory interneurons, and the synaptic terminals of other descending pathways.Answer: b1. Where would the cell body of a sensory neuron that transmits touch information from the cheek to the central nervous system be located? a. Ganglion alongside the brainstem b. Nucleus inside the brainstem c. Ganglion alongside the spinal cord d. Nucleus inside the spinal cord e. Ganglion immediately underneath the skin of the cheekAnswer: a2. Which feature is characteristic of the pseudounipolar neurons of the somatosensory system? a. Central and peripheral components of the fibers are of a similar length b. Thick fibers that enables fast signal transduction c. Fibers with particularly high myelin content d. Continuous fibers, with the cell body attached by a single process e. Multiple dendritesAnswer: d3. Afferent fibers that lack specialized receptors at their terminals detect which type of stimuli? a. Touch b. Vibration c. Pressure d. Pain e. ItchAnswer: d4. Which afferent fibers have the largest diameter? a. Ia sensory afferents from the muscles b. Ia sensory afferents from the skin c. Aβ sensory afferents from the skin d. A and C fibers that conduct temperature information e. A and C fibers that conduct pain informationAnswer: a5. The _______ is inversely proportional to the density of the fibers supplying an area. a. diameter of the afferent fiber b. size of the receptive field c. speed of conduction d. average stimulus strength e. distance between an area and the central nervous systemAnswer: b6. On which body part would the two-point discrimination threshold be shortest? a. Thigh b. Foot c. Arm d. Thumb e. EarAnswer: d7. Rapidly adapting fibers are most likely to provide information about the _______ of a stimulus. a. shape b. weight c. texture d. movement e. temperatureAnswer: d8. Which type of somatosensory afferents transmit information from touch mechanoreceptors to the central nervous system? a. Ia b. II c. Aβ d. Aδ e. CAnswer: c9. Which afferents have the highest spatial resolution? a. Merkel afferents b. Meissner afferents c. Pacinian afferents d. Ruffini afferents e. Pain afferentsAnswer: a10. Meissner afferents account for about _______ of the mechanosensory innervation of the human hand. a. 10% b. 25% c. 40% d. 75% e. 90%Answer: c11. Merkel afferent fibers convey information about which variable(s)? a. Motion detection b. Temperature c. Proprioception d. Shape and texture e. Subtle vibrationsAnswer: d12. The longitudinal lanceolate endings do not respond to a. deflection of the hair by strokes on the skin. b. movement of air over the skin surface. c. sensual touch. d. gentle caress. e. pain.Answer: e13. A dermatome is an area innervated by a. fibers of the cells from a single dorsal root ganglion. b. the axon of a single neuron. c. fibers from one spinal cord segment. d. fibers with similar properties. e. fibers of the cells from a single nucleus in the brain stem.Answer: a14. Which component of the musculoskeletal system is responsible for force-production? a. Muscle spindle b. Intrafusal muscle fiber c. Extrafusal muscle fiber d. Sensory afferents e. Connective tissue capsuleAnswer: c15. Which sensation would be affected if group II sensory afferents in a limb were rendered dysfunctional due to a mutation? a. Velocity of limb movement b. Direction of limb movement c. Touch to the limb d. Static position of the limb e. Change in muscle lengthAnswer: d16. Which role do γ motor neurons play in the function of a muscle spindle? a. They improve the accuracy of the reported sensory information by innervating extrafusal fibers. b. They improve the accuracy of the reported sensory information by innervating intrafusal fibers. c. They enhance the force of muscle contraction by innervating extrafusal fibers. d. They enhance the force of muscle contraction by innervating intrafusal fibers. e. They coordinate the contraction of extrafusal and intrafusal fibers.Answer: b17. Muscles in which region would most likely have the lowest density of muscle spindles? a. Tongue b. Extraocular c. Hand d. Neck e. LegAnswer: e18. Joint receptors are important to perception which information? a. Joint position near the limits of normal range of motion b. Joint movement c. Finger position near the limits of normal range of motion d. Finger movement e. Limb position and movementAnswer: c19. The axons of the medial lemniscus synapse with neurons of the a. primary sensory cortex. b. thalamus. c. gracile nucleus. d. cuneate nucleus. e. dorsal root ganglion.Answer: b20. Tactile information from the face to the central nervous system follows which pathway? a. Cutaneous receptors, trigeminal ganglion, pons, VPL of thalamus, ipsilateral cortex b. Cutaneous receptors, trigeminal ganglion, trigeminal brainstem complex, VPL of thalamus, contralateral cortex c. Cutaneous receptors, cranial nerve V, trigeminal brainstem complex, VPM of thalamus, contralateral cortex d. Cutaneous receptors, dorsal root ganglion, trigeminal brainstem complex, VPM of thalamus, ipsilateral cortex e. Cutaneous receptors, dorsal root ganglion, dorsal column nuclei, VPM of thalamus, cortexAnswer: c21. Where are the bodies of the cells that innervate proprioceptors of the face located? a. Cervical dorsal root ganglia b. Thoracic dorsal root ganglia c. Trigeminal ganglia d. Mesencephalic trigeminal nucleus e. Principal nucleusAnswer: d22. Organization in which region of the brain is represented as a complete somatotopic map? a. Primary somatosensory cortex SI b. Brodmann's area 1 c. Brodmann's area 2 d. Secondary somatosensory cortex SII e. HypothalamusAnswer: a23. Refer to the figure. Activity of which cortical area(s) depend(s) on the projections from other cortical areas? a. Secondary somatosensory cortex only b. Brodmann's areas 1 and 2 only c. Brodmann's areas 3a and 3b d. Secondary somatosensory cortex and Brodmann's areas 1 and 2 e. Parietal areas 5 and 7Answer: d24. Functional reorganization in the brain a. occurs at all ages, all of the time. b. occurs after nerve damage, amputation, and skill training. c. results in a temporary loss of sensory input. d. occurs only during the first ten years of life. e. occurs only in the cortex.Answer: b1. What change could improve the two-point discrimination of a region of skin?Answer: An increase in the density of innervation and reduction of the receptive field size2. What is a somatosensory receptive field?Answer: The surface area over which stimulation results in a significant change in the rate of action potentials of a particular neuron.3. What is proprioception? Name three kinds of proprioceptors.Answer: Proprioception is the ability to sense the position of the body and limbs in space. Muscle spindles, Golgi tendon organs, and joint receptors are types of proprioceptors.4. Where are the gracile and cuneate tracts located, and what information do they convey?Answer: The gracile tract lies in the medial dorsal column of the spinal cord and conveys information from the lower limbs; the cuneate tract lies in the lateral dorsal column of the spinal cord and conveys information from the upper limbs, trunk, and neck.14. The _______ of the trigeminal _______ conveys facial tactile information in much the same way that the dorsal column nuclei transmit lower body tactile information. a. principal nucleus; complex b. spinal nucleus; complex c. ophthalmic branch; nerve d. mandibular branch; nerve e. maxillary branch; nerveAnswer: aA diabetic patient has two microneedles simultaneously inserted into their arm at close proximity for blood-glucose sampling. The patient perceives the insertion of these needles as one painful stimulus rather than two separate ones. What may be the reason for this? a. The upper arm has a larger two-point discrimination threshold than the distance between the electrodes, resulting in the perception of one stimulus. b. There was damage to the circumferential ending surrounding one hair follicle, so only one pain stimuli could be detected. c. The two microelectrodes being inserted simultaneously resulted in the sensory nerves being unable to distinguish between the two stimuli. d. The hairy skin lacks free nerve endings, resulting in the brain being unable to distinguish different pain sensations.The upper arm has a larger two-point discrimination threshold than the distance between the electrodes, resulting in the perception of one stimulus.A patient experiences a traumatic brain injury, disputing the transmission of sensory signals to the thalamus. How will this affect processing of proprioceptive and cutaneous sensations? a. While the primary somatosensory cortex will be unaffected, the secondary somatosensory cortex will no longer receive sensory signals to process. b. Cutaneous sensations will no longer to be processed in the brain, while proprioceptive sensations will be processed normally. c. While neither will be able to reach the cortex, proprioceptive sensations will still be processed by the cerebellum for motor processing. d. Neither cutaneous nor proprioceptive sensations will be able to reach the brain.While neither will be able to reach the cortex, proprioceptive sensations will still be processed by the cerebellum for motor processing.What is the primary difference between rapidly adapting afferents and slowly adapting afferents? a. Rapidly adapting afferents typically innervate the skin, while slowly adapting afferents innervate the muscle b. Rapidly adapting afferents only continuously respond to dynamic stimuli, while slowly adapting afferents continuously respond to static stimuli. c. Rapidly adapting afferents innervate around hair follicles, where slowly adapting afferents do not. d. While rapidly adapting afferents can be found in both hairy skin and glabrous skin, slowly adapting afferents only innervate glabrous skin.Rapidly adapting afferents only continuously respond to dynamic stimuli, while slowly adapting afferents continuously respond to static stimuli.What region of the brain may be targeted with stimulation therapy in order to alleviate chronic pain in a patient's leg? a. The ventral posterior medial nucleus of the thalamus b. Periaqueductal gray c. Anterior cingulate d. Somatosensory cortexPeriaqueductal grayWhich of the following is FALSE regarding phantom limbs? a. The effects of the phantom limb evolve for years after injury due to maladaptive neuroplasticity. b. Phantom limbs have only been reported in amputee patients and those with traumatic injuries to the nervous system. c. Patients with phantom limbs have reported chronic 'phantom pain', and this pain is immune to pain treatments like ablation of the sensory pathway. d. Phantom limbs are extremely common in amputees, with most reporting sensations where the amputated limb was located.Phantom limbs have only been reported in amputee patients and those with traumatic injuries to the nervous system.Which of the following is true regarding peripheral nociceptors? a. Typically have slow conduction velocities b. Soma have been found in the spinal cord, resulting in chronic spinal cord pain. c. All have myelinated axonal tracts d. Can be classified as Aδ and Aβ fibersTypically have slow conduction velocitiesWhich statement about sensitization is FALSE? a. Peripheral sensitization has been associated with an increased risk of infection at the injury site. b. There is an increased number of action potentials in nociceptors by the dorsal spinal cord. c. There is an increased release of chemicals by both neuronal and non-neuronal cells near the injury site. d. Damage to the nerve fibers can result in long-lasting sensitization.Peripheral sensitization has been associated with an increased risk of infection at the injury site.Which describes the mechanism of which capsaicin interacts with nociceptors a. Block potassium channels, causing an increase in resting membrane potential. b. Opens TRPV1 ion channels. c. Opens chloride ion channels to prevent action potentials d. Capsaicin inactivates astrocytes, resulting in an increase in glutamate.Opens TRPV1 ion channels.Gracile nucleus or cuneate nucleus Upper body or lower bodyGracile nucleus, and innervates the lower bodyGracile nucleus or cuneate nucleus Upper body or lower bodyCuneate nucleus, and innervates the upper bodyIa and II afferent axonsSensory Function: proprioception Receptor Type: muscle spindle Axon diameter: largest Velocity: fastestAβ afferent axonsSensory Function: touch Receptor Type: merkel, meissner, pacinian, and ruffini cells Axon diameter: second largest Velocity: second fastestAδ afferent axonsSensory Function: pain, temperature Receptor Type: free nerve endings Axon diameter: second smallest Velocity: second slowestC afferent neuronsSensory Function: pain, temperature, itch, non-discriminative touch Receptor Type: unmyelinated free nerve endings Axon diameter: smallest Velocity: slowestMerkel cells- shape and texture perception - static components, pressure - small receptive field - highest spatial resolution - sustained, slow adaptationMeissner's corpuscles- motion detection, grip control -intermediate receptive field -intermediate spatial resolution - rapid adaptationPacinian corpuscles- vibrations - grasping objects - large receptive field - low spatial resolution - rapid adaptionRuffini corpuscles- skin stretch - large receptive field - low spatial resolution - sustained, slow adaption least understood