List of Contributors. Preface. Acknowledgements. 1. Anatomy and physiology of descending control of nociceptive responses of dorsal horn neurons: comprehensive review (Wm. D. Willis, Jr.). 2. Anatomy, physiology and pharmacology of the periaqueductal gray-contribution of antinociceptive controls (D. B. Reichling, G.C. Kwiat and A.I. Basbaum). 3. Direct and indirect pathways to lamina I in the medulla oblongata and spinal cord of the cat (G. Holstege). 4. Peptidergic neurons in the nucleus raphe magnus and the nucleus gigantocellularis: their distributions, interrelationships, and projections to the spinal cord (R.M. Bowker, L.C. Abbott and R.P. Dilts). 5. Spinal dorsal horn circuitry involved in the brain stem control of nociception (M.A. Ruda). 6. Stimulation-produced analgesia in animals: behavioural investigations (J.-L. Oliveras and J.-M. Besson). 7. Stimulation-produced antinociception (J.O. Dostrovsky). 8. Studies of PAG/PVG stimulation for pain relief in humans (N.M. Barbaro). 9. Problems and controversies in PVG and sensory thalamic stimulation as treatment for pain (B.A. Meyerson). 10. Current issues regarding subcortical electrical stimulation for pain control in humans (Y. Hosobuchi). 11. Tonic descending inhibition and spinal nociceptive transmission (A.W. Duggan and C.R. Morton). 12. Discussion of the paper by A.W. Duggan and C.R. Morton, entitled "Tonic descending inhibition and spinal nociceptive transmission" (J.G. Collins). 13. The effect of behavioral state on the sensory processing of nociceptive and non-nociceptive information (R. Dubner). 14. Discussion: Descending modulation in the trigeminal system (B.J. Sessle). 15. Discussion of the paper by Ronald Dubner: The effect of behavioral state on the sensory processing of nociceptive and non-nociceptive information (K.L. Casey). 16. Effects of morphine given in the brain stem on the activity of dorsal horn nociceptive neurons (G.F. Gebhart and S.L. Jones). 17. Brain stem neuronal circuitry underlying the antinociceptive action of opiates (H.L. Fields, N.M. Barbaro and M.M. Heinricher). 18. Some views on the influence of morphine on brain stem pain modulating neurons and descending controls acting on the spinal cord (A. Dickenson). 19. Endogenous opioid peptides in the descending control of nociceptive responses of spinal dorsal horn neurons (A. Herz and M.J. Millan). 20. Electrophysiological evidence for the activation of descending inhibitory controls by nociceptive afferent pathways (D. Le Bars and L. Villanueva). 21. Paradoxical effects of low doses of naloxone in experimental models of inflammatory pain (V. Kayser, J.-M. Besson and G. Guilbad). 22. Intrathecal administration: methodological considerations (D.L. Hammond). 23. Neuronal effects of controlled superfusion of the spinal cord with monoaminergic receptor antagonists in the cat (J. Sandkühler and M. Zimmerman). 24. Pharmacology of putative neurotransmitters and receptors: 5-hydroxytryptamine (M.H.T. Roberts). 25. The use of microiontophoresis in the study of the descending control of nociceptive transmission (R.G. Hill). 26. Serotonin receptor subtypes and the modulation of pain transmission (R.G. Hill). 27. Pharmacologic evidence for the modulation of nociception by noradrenergic neurons (H.K. Proudfit). 28. Sites of action of opiates in production of analgesia (T.L. Yaksh, N.R.F. Al-Rodhan and T.S. Jensen). 29. Intracerebroventricular morphinotherapy for control of chronic cancer pain (Y. Lazorthes, J.-C. Verdié, B. Caute, R. Maranhao and M. Tafani). 30. Endogenous opioids and pain: status of human studies and new treatment concepts (R.C.A. Frederickson and R.E. Chipkin). 31. Significance of opioid peptides and other potential markers of neuropeptide systems in cerebrospinal fluid (L. Terenuis). 32. In vivo and in vitro release of central neurotransmitters in relation to pain and analgesia (M. Hamon, S. Bourgoin, D. Le Bars and F. Cesselin). Subject Index.