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Flashcards in Medial Pain Deck (15)
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1
Q

Nociception vs. Pain

A

-Pain is emotion, nociception is sensation

2
Q

Five main functions of the medial pain system

A
  • Limbic and autonomic activation
  • Learning and anticipation
  • Nocifensive behavior
  • Empathy
  • Inhibition
3
Q

Three main ascending spinal pain systems

A
  • Anterolateral system (direct): includes neospinothalamic tract (axons primarity in lamina 4 of dorsal hort, travel in lateral funiculus to VPL and then somatosensory cortex)
  • Anterior lateral pathways (indirect): controls limbic, autonomic, endocrine and motor components of pain, and the activation of pain-inhibiting circuits. Bilateral ascention, multiple synapses
  • Posterior medial pathways: visceral nociceptive information in gut. Lamina X neurons synapse in gracile nucleus and then project of VPL and CL of thalamus, then to insula and anterior cingulate cortex
4
Q

3 indirect anterior lateral ascending pathways

A
  • Paleospinothalamic: ascend bilaterally, synapse in RF and MITN, project to limbic cortical and subcortical areas (ACC and insula)
  • Spinoreticular: ascend bilaterally, terminate at two different levels of RF (caudal sends back to IML cell column, rostral RF and LC innervate PVN and MITN)
  • Spinomesencephalic: Parabrachial nucleus and PAG, visceral info, PAG regulates ANS and alters signals to amygdala, inhibit pain sensation
5
Q

Referred pain

A

-Some visceral nociceptive info synapses in neurons in the dorsal horn which can be perceived as cutaneous pain from segmentally related dermatomes.

6
Q

Myelotomy/Cordotomy

A
  • For intractable visceral pain

- Deafferent the source of the pain signal-posterior midline myelotomy

7
Q

Reticular formation subdivisions important for pain

A

-LC, parabrachial area, nucleus gigantocellularis, raphe nucleus

8
Q

Key projections of RF, LC, MITN, and PAG

A
  • Innervate key upper and lower limbic/autonomic/motor structures
  • Nucleus ambiguus
  • Gigantocellular RF that projects to the sympathetic IML
  • Parabrachial nucleus
  • Paraventricular nucleus of hypothalamus
  • Amygdala
  • ACC
  • Support limbic/autonomic activation!!!!!
9
Q

Cingulate activation in the medial pain system

A
  • Motor and limbic areas strongly activated
  • Noxious visceral stimuli more rostral than cutaneous stimulations
  • Activation also includes supplementary motor area and cingulate motor area–motor planning
10
Q

Medial pain system interaction with limbic system

A

-Allows limbic system to assign emotional weights to stimuli (rating unpleasantness activates ACC, attending to location activates MCC)

11
Q

Anticipation/learning and Nocifensive Behavior

A
  • Contingent negative variations appear in EEG recordings several seconds after a fear inducing stimulus
  • ACC activity co-varies with amplitude of this potential
  • Anticipation of pain is a learning event in the medial pain system
12
Q

Central sensitization

A
  • Maladaptive learning
  • Noxious stimulus leads to greater intracellular Ca2+
  • Sensitized nociceptors have greater amounts of Ca2+ which causes long periods of abnormal depolarization in spinal cord neurons and their targets
  • Unchecked central sensitization processes can lead to a state of near constant nociceptor firing and thus chronic pain
13
Q

Pain empathy

A
  • Seeing pain inflicted on others activates lateral nociceptive and medial pain systems
  • Can evoke equivalent emotions and sympathy pain
14
Q

Anterior cingulotomy

A
  • Treatment of debilitating chronic pain
  • Abolishes nocifensive and many limbic/autonomic responses
  • Patients can still localize noxious stimuli
  • Can feel the stimulus but don’t care
15
Q

Pain inhibition

A
  • Magnetic cortical stimulation gives significant pain relief
  • Increased ACC activation and consequent PAG activation
  • MCS activates descending pain signaling pathways from ACC