EX1; Central Pain

Question 1

These nociceptors terminate mainly in the superficial laminae (I, II), although there is an important termination in layer V too; in the medullary dorsal horn (n. caudalis)

Answer 1

A-delta

c-polymodal

Question 2

Non-nociceptive terminals are mainly where

Answer 2

in the deep laminae of the medullary dorsal horn

Question 3

Following a peripheral nerve injury, there is postganglionic degeneration of what

Answer 3

c-fiber terminals in the superficial layers of the dorsal horn

Question 4

Upon c-fiber degeneration in the dorsal horn after injury, what becomes of that A-fibers

Answer 4

the A-fibers in the deeper layers can sprout into the superficial layers, activating 2nd order pain signaling neurons in the superficial layer

Question 5

What two types of neurons are found in the medially dorsal horn

Answer 5

nociceptive specific neurons

wide dynamic range neurons

Question 6

This neuron represents convergence of a nociceptive neuron and a low-threshold A-beta type low threshold (non-nociceptive) type cell

Answer 6

wide-dynamic range neuron

Question 7

Wide-dynamic range neurons may also have this, in which the center area is excitatory to pain and touch (wide-dynamic) but the surround is inhibitory to pain stimuli

Answer 7

“center surround” receptive-field organization

Question 8

Activation of the center-surround receptive field may be involved with what

Answer 8

referred pain

Question 9

Wide-dynamic range neurons in nucleus caudalis responds to what different type of stimuli

Answer 9

referred pain
innocuous and noxious stimuli
light touch and pressure to facial region
painful pinch and heat
electrical stimulation of TMJ and tooth pulp

Question 10

True or False

the nucleus caudalis is the only part of the trigeminal complex that processes oral pain

Answer 10

False; it is not the only part

Question 11

One frequent observation in trigeminal pain is that it is what

Answer 11

referred; pathology or insult to one area results in pain experienced somewhere else

Question 12

Referred pain is partially explained by what in the MDH

Answer 12

convergence; pain and non-pain afferents converge on “pain-signaling” neurons

Question 13

These fibers carry the pain message from the secondary hyperalgesia zones to the brain

Answer 13

A-beta fibers

Question 14

How is it that the normal light touch sensation A-beta fibers carry pain signals to the brain

Answer 14

normal A-beta fibers release glutamate but is ineffective at the synapse because of Mg+ block in the NMDA receptor, intense pain via a C-fiber sensitizes (removes Mg block) the postsynaptic neuron to non-painful beta input

Question 15

What three things involve MDH neuron response involving c-fiber activation of a-beta

Answer 15

depolarization by substance P
modification of NDMA receptor (remove Mg block)
increase conductance of NMDA receptor
respons to innocuous stimuli induces pain

Question 16

What are the pain thresholds for healthy vs unhealthy teeth

Answer 16

high pain threshold for normal teeth
much lower pain threshold for inflamed teeth
lower pain threshold in contralateral healthy teeth; due to ipsilateral innervation

Question 17

The inflamed teeth are “sensitizing” central neurons with what input

Answer 17

from healthy contralateral side to make them more sensitive

Question 18

What other region in the has been shown to also be a “pain center” besides nucleus caudalis

Answer 18

nucleus oralis

Question 19

True or False

Not all oral and facial pain is mediated by trigeminal fiber terminating in MDH

Answer 19

True

Question 20

What two aspects of pain cannot be explained by brainstem mechanisms

Answer 20

perceptual and emotional components in the forebrain

Question 21

Pain fibers terminate in midline thalamic nuclei including the nucleus submedius which projects to the cingulate cortex which then deals with which aspect of pain

Answer 21

emotional

Question 22

Pain fibers rom the MDH cross and ascend in trigeminothalamic tract to terminate in the ventral posterior lateral nucleus (VPL) then to the somatosensory cortex which then deals with which aspect of pain

Answer 22

discrimination (localization); where is the pain, how intense is it, etc.

Question 23

Other aspects of pain response including some reflex action is mediated by which part of the brainstem

Answer 23

reticular formation

Question 24

What is specific about the neural response regarding the N. submedius and CC

Answer 24

neural response outlasts stimulus (poor localization)

also large receptive field

Question 25

N. submedium and CC also deal with this

Answer 25

activity associated with anxiety

Question 26

What is specific about the neural response regarding the VPL and somatosensory cortex

Answer 26

neural response track pain stimulus; onset and offset follow the stimulus closely

Question 27

What is the receptive field like involving VPL and SS complex

Answer 27

small

Question 28

Forebrain pathways modulate pain perception involving these two sensations

Answer 28

anxiety can increase pain perception

the placebo effect suppresses pain perception

Question 29

There is correlation between anxiety level and degree of activation of that what

Answer 29

anterior cingulate cortex

Question 30

This system is implicated in the placebo effect

Answer 30

endogenous opioid system; the perception of pain can be diminished when a patient believes they are taking medicine

Question 31

Upon blocking of the endogenous opioid system, what happened to the pain levels

Answer 31

the pain levels felt increased