Descending control of nociception: Specificity, recruitment and plasticity

Abstract The dorsal horn of the spinal cord is the location of the first synapse in pain pathways, and as such, offers a very powerful target for regulation of nociceptive transmission by both local segmental and supraspinal mechanisms. Descending control of spinal nociception originates from many b...

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Bibliographic Details
Published in:Brain Research Reviews 2009-04, Vol.60 (1), p.214-225
Main Authors: Heinricher, M.M, Tavares, I, Leith, J.L, Lumb, B.M
Format: Article
Language:English
Subjects:
Animals
Antinociception
Biological and medical sciences
Brain Stem - anatomy & histology
Brain Stem - physiology
Brainstem
Caudal ventrolateral medulla
Efferent Pathways - anatomy & histology
Efferent Pathways - physiology
Fundamental and applied biological sciences. Psychology
Humans
Medulla Oblongata - cytology
Medulla Oblongata - physiology
Nerve Fibers, Unmyelinated - physiology
Neural Inhibition - physiology
Neurology
Nociceptors - physiology
Pain - physiopathology
Pain modulation
Periaqueductal gray
Posterior Horn Cells - physiology
Pronociception
Raphe
Reticular Formation - cytology
Reticular Formation - physiology
Somesthesis and somesthetic pathways (proprioception, exteroception, nociception)
interoception
electrolocation. Sensory receptors
Spinal Cord - anatomy & histology
Spinal Cord - physiology
Vertebrates: nervous system and sense organs
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Summary:Abstract The dorsal horn of the spinal cord is the location of the first synapse in pain pathways, and as such, offers a very powerful target for regulation of nociceptive transmission by both local segmental and supraspinal mechanisms. Descending control of spinal nociception originates from many brain regions and plays a critical role in determining the experience of both acute and chronic pain. The earlier concept of descending control as an “analgesia system” is now being replaced with a more nuanced model in which pain input is prioritized relative to other competing behavioral needs and homeostatic demands. Descending control arises from a number of supraspinal sites, including the midline periaqueductal gray-rostral ventromedial medulla (PAG-RVM) system, and the more lateral and caudal dorsal reticular nucleus (DRt) and ventrolateral medulla (VLM). Inhibitory control from the PAG-RVM system preferentially suppresses nociceptive inputs mediated by C-fibers, preserving sensory-discriminative information conveyed by more rapidly conducting A-fibers. Analysis of the circuitry within the RVM reveals that the neural basis for bidirectional control from the midline system is two populations of neurons, ON-cells and OFF-cells, that are differentially recruited by higher structures important in fear, illness and psychological stress to enhance or inhibit pain. Dynamic shifts in the balance between pain inhibiting and facilitating outflows from the brainstem play a role in setting the gain of nociceptive processing as dictated by behavioral priorities, but are also likely to contribute to pathological pain states.
ISSN:0165-0173
1872-6321
DOI:10.1016/j.brainresrev.2008.12.009