1. The Puzzle of Pain The Reverend Dr. David CM Taylor http://pcwww.liv.ac.uk/~dcmt/painpuz.ppt

2. “The Puzzle of Pain”

3. “Tell me where it hurts…”

4. There is more than one....

5. Gate Control Theory Melzack and Wall in 1968 rubbing injured region decreases pain sensation detail wrong but useful

6. Descending Inhibition Touch cortico-thalamic pathways why we don’t feel clothes Pain battle and sporting injuries, ecstasy children, animals, elderly/suffering

7. Descending control of pain microinjection of opiates into discrete regions of the CNS (PAG,limbic system, SG) produces analgesia Microstimulation there also produces analgesia Opioid peptides are present there Electrical stimulation of the PAG or NRM produces analgesia

8. Just for re-orientation

9. Proposed mechanism limbic system periaqueductal grey nucleus raphe magnus interneurones in lamina II of spinal cord

10. Scratch pad if needed

11. Presynaptic hypothesis from brain to brain substance P fibre 5HT enkephalin pioneered by Leslie Iversen

12. How might control work? Electrical (“Sherringtonian or…”) Shorter action potentials, Altered levels of “second messengers” less Ca 2+, less transmitter release, less activity Chemical Alter gene expression Change level or type of transmitter released or Receptors on post synaptic cells

13. Post-synaptic hypothesis from brain to brain c-fibre “pain” A  fibre touch This is the currently accepted “gate control” theory