Part 1 Flashcards
the final experience of pain results from concerted actions of what three orders of brain processing?
nociceptive matrix (ascending to thalamus, amygdala, reticular formation, SS regions)
perceptual/attentive matrix (ant insula and cingulate cortices)
reappraisal/emotional matrix (PFC)
nociceptors enter the dorsal or ventral horn?
dorsal spinothalamic tracts
Adelta neurons go to which types of lamina?
I and V
C neurons go to which types of lamina?
1 and II
What do Lamina I neurons respond to?
nociceptive, but also respond to warm, cold, itch and other innocuous stimuli
Which laminar neurons are wide dynamic range neurons?
Lamina V
What type of information do Lamina V neurons transmit? What neurons converge into Lamina V?
signals pain intensity and mechanical stimuli. Abeta (mechanical, chemical and thermal stimuli) and Adelta and C (pain)
Axons of lamina I and V decussate and form the _____________ pathway that projects to the______
ascending anterolateral pain pathway projects to the posterior thalamus
Which neuron type detects fast pain, sharp pricking sensations and has a high threshold?
Adelta fibers (mechano- and thermoreceptors)
Which neuron type detects slow pain, dull achy burning pain and can have a high or low threshold?
C fibers (mechano-, chemo- and thermoreceptors)
What three areas of cortex does that thalamus project to? What does this accomplish?
SS cortex, posterior insula and the cingulate cortex. this generates somato-specific conscious perception and vegetative responses to the pain sensation
The A5-7 spinothalamic tract into the reticular formation generates:
a NE pathway to the cortex/spinal cord for attention/arousal
The parabrachial tract into the reticular formation generates:
a pathway to the amygdala
The spinothalamic tract to the periaqueductal gray in the reticular formation generates:
a descending pathway that controls the sensitivity to pain
What areas of cortex does the perceptual matrix project to? What does this activity generate?
anterior insula, anterior, cingulate, PFC and posterior parietal cortex. this transforms vegetative reactions into internal feelings
How does the cingulate cortex react to pain? (What does it do?)
emotional aspects of pain- decides on behavioral patterns based on the experience
What does the insula do in response to pain?
integrates apppetitive and aversive valence of pain with the impact it will have on the body state
What 4 areas does the parabrachial nucleus in the RF project to? What is this circuit called?
amygdala, periaqueductal grey, hypothalamus, ventrolateral medulla. (results in sympathetic activation of physiologic systems).
spino-parabrachial-amygdala circuit
What does the amygdala do in response to pain sensation from the parabrachial nucleus?
generates anxiety, fear conditioning, antinociception, autonomic adjustments
What are some physiological effects of sympathetic activation generated by the spino-parabrachial-amygdala circuit?
diversion of blood to vital organs, increased HR and BP, increased RR, glyconeogenesis and glycogenolysis
the periaqueductal grey recieves input from what three sources? What is it involved in?
input from: ascending spinothalamic tracts, indirectly via the parabrachial nucleus, from the amygdala
involved in: defense responses (fight/flight) and supraspinal pain regulation
The defense responses generated by the periaqueductal grey are regulated by what 5 areas?
cingulate, insula, amygdala, hypothalamus, PFC
What two zones of defense responses does the PAG generate?
the ventrolateral (passive coping) and the lateral zone (active coping)
What are some aspects of the ventrolateral zone?
passive emotional coping, inhibition of sympathetic activity, wihtdrawl, disengagement, immobility, hyporeactivity, long-lasting opiod mediated analgesia
What are some aspects of the lateral zone?
active emotional coping, Rostral (FIGHT), caudal (FLIGHT), excitation of sympathetic activity, short-lasting opiod mediated analgesia
What is the descending pain pathway for supraspinal pain regulation? what is the central figure of this pathway and what is it responsible for?
cingulate cortex–> hypothalamus –>PAG –>reticular nuclei –>dorsal horn
PAG is central figure that is responsible for stress-induced hypoalgesia
What two things does the PAG project down to?
A5-7 reticular nuclei and the raphe
cells in the raphe nucleus that are stress mediated and induce tonic inhibition of pain transmission use what NT?
serotonin
What do non-serotonergic cells in the raphe nucleus mediate? What kind of mechanisms do the OFF cells use?
regulates immediate pain, alerting and arousal. ON cells facilitate pain transmission. OFF cells inhibit pain transmission via opiod mechanisms
What kind of NT do the A5-7 nuclei use? What does this do?
Norepineprhine (to inhibit pain transmission from alpha2 receptors)
What activates opiods?
painful stimuli
What do opiods and cannabinoids do?
upregulate the activity of medullary raphe OFF cells (to inhibit pain transmission)
how do tricyclic antidepressants and NE reuptake inhibitors enhance antinociceptive effects of opiods?
by increasing the availability of spinal NE (remember that A5-7 use NE to inhibit pain transmission)