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The Puzzle of Pain

The Puzzle of Pain. The Reverend Dr. David CM Taylor http://pcwww.liv.ac.uk/~dcmt/painpuz.ppt. “The Puzzle of Pain”. “Tell me where it hurts…”. There is more than one. Gate Control Theory. Melzack and Wall in 1968 rubbing injured region decreases pain sensation detail wrong but useful.

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The Puzzle of Pain

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

  12. How might control work? • Electrical (“Sherringtonian or…”) • Shorter action potentials, • Altered levels of “second messengers” • less Ca2+, 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 A fibre touch to brain c-fibre “pain” This is the currently accepted “gate control” theory

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