NEUROANATOMY OF THE PAIN SYSTEM AND OF THE PATHWAYS THAT MODULATE PAIN

We review many of the recent findings concerning mechanisms and pathwa ys for pain and its modulation, emphasizing sensitization and the modu lation of nociceptors and of dorsal horn nociceptive neurons. We descr ibe the organization of several ascending nociceptive pathways, includ ing the spinothalamic, spinomesencephalic, spinoreticular, spinolimbic , spinocervical, and postsynaptic dorsal column pathways in some detai l and discuss nociceptive processing in the thalamus and cerebral cort ex. Structures involved in the descending analgesia systems, including the periaqueductal gray, locus ceruleus, and parabrachial area, nucle us raphe magnus, reticular formation, anterior prerectal nucleus. thal amus and cerebral cortex, and several components of the limbic system are described and the pathways and neurotransmitters utilized are ment ioned. Finally, we speculate on possible fruitful lines of research th at might lead to improvements in therapy for pain.