Medical Pain Systems & Limbic-motor interaction Flashcards
How is pain different from nociception?
Pain is a perception or the conscious experience associated with nociception
Nociception is the process within the PNS/CNS that is associated with noxious stimuli
What are the five main functions of the medial pain system?
- Limbic and ANS activation
- Learning and anticipation
- Nocifensive behavior (defense mechanism for pain)
- Empathy
- Inhibition
What are the three main ascending spinal pain systems? What information is carried by each of these systems?
- Direct anterolateral pathway- carries pain, temp, and simple tactile sensation
- Indirect anterolateral pathway- controls the limbic/endocrine/motor components of pain; associate emotion with pain
- Posterior medial pathway- visceral nociceptive info from the gut that conveys pain, temp, irritation and chemical changes– poor localization
The neospinothalmic tract is a direct anterolateral system tract. Where do the sensory neurons enter and how does it continue up to the postcentral gyrus?
Receptors from pain or temp have axons that enter the dorsal horn, synapse and then cross over to the ALS. From there the axons ascend and go to the VPL in the thalamus and from there to the post central gyrus
The paleospinothalamic tract is an indirect anterolateral system tract. In which part of the spinal cord do these axons ascend? Where do they synapse after getting to the brain? Where do they terminate?
Ascend in the ventrolateral spinal cord bilaterally
Synapse in the reticular formation of the brain stem as well as the intralaminar thalamic nuclei
Termiates in the anterior cingulate gyrus and the insula
The spinoreticular tract is an indirect anterolateral system tract. In which part of the spinal cord do these axons ascend? Where do they terminate?
Axons ascend bilaterally and terminate at two different sites within the reticular formation: the caudal reticular formation (sending projections back to the intermediolateral column) and the rostral reticular formation and locus coerulus
The spinomesencephalic tract is an indirect anterolateral system tract. Where do they terminate?
Terminate in the midbrain and the PAG - the PAG neurons regulate ANS and transmit info to the amygdala
Referred pain arises because some of the visceral afferents project to which tract rather than the posterior medial pathway?
Spinomesencephalic
What 4 structures are part of the reticular formation?
- Raphae nucleus 2. Locus coerleus 3. Parabrachial area 4. Nucleus gigantocellularis
The locus coerulus coordinates the neuroendocrine and limbic system responses. What does the locus coerulus release? What does this cause?
Releases norepinephrine
The leads to the release of ACTH from PVN of hypothalamus
What is pain empathy? What is seen on EEG?
Seeing pain afflicted on others which activates the lateral nociceptive and medial pain systems
How is the medial pain pathway different from the anterolateral pathway?
The medial pain pathway terminates on the medial surface of the cingulate gyrus
Contingent negative variations are seen on EEG when someone is conditioned to be fearful of a stimulus. What was identified as the source of the contingent negative variations?
Anterior cingulate gyrus, medial motor areas (SMA, CMA) and the midline intramlaminar thoracic nucleus (MITN)
Given the anterior cingulate gyrus’ role in the medial pain system. What would happen with an anterior cingulotomy?
Lose nociception as well as the autonomic/limbic response.
The patient still reports feeling pain, but doesn;t care or isn’t bothered by it
This is used in patients with chronic pain
What is activated when patients are asked to rate the unpleasantness of noxious heat stimuli?
the medial pain system, which is ACC and PAG
