Lecture 7

Question 1

what fibres does pain occur in?

Answer 1

anterolateral tract (A and C type fibres)

Question 2

what is pain in teh CNS mediated by?

Answer 2

1. Cerebral cortex
   
   • primary and secondary somatosensory cortex
   • ACG
   • Insula
   • PFC
2. Brainsten
   
   • periaqueductal gray
   • reticular formation
3. spinal cord
   
   • dorsal horn grey matter

Question 3

how does the primary somatosensory function in pain?

Answer 3

• conveys location and intensity of pain
• sensory discriminative
• A delta more input?

Question 4

how does the ACG function in pain?

Answer 4

• autonomic-neuroendocrine response
• affective component
• evaluates the intensity of noxious stimuli
• C fibres more important

Question 5

how does the PFC function in pain?

Answer 5

-involved in attention–DISTRACTION works here

Question 6

what are the criteria for gate control?

Answer 6

1. a gate which controls afferent impulses to the SC neurons
2. short and large diameter fibres control activity of gate
3. impulses from higher centres modulate the SC neurons
4. SC neurons reach/exceed critical point–“action sysmte” activates–>pain!

Question 7

what are the structures involved in persistent and chronic pain?

Answer 7

C type fibres, reticulothalamic tract, grey matter in spinal cord/brainstem, cortex (anterior cingulate gyrus and insula)