Nucleus Raphe Magnus (NRM)

Description of the raphe nuclei (from wikipedia & Michelson et al.)

The raphe nuclei are a series of seven nuclei located in the medial portion of the reticular formation. In order from caudal to rostral, the raphe nuclei are known as the nucleus raphe obscurus, the raphe magnus, the raphe pontis, the raphe pallidus, the nucleus centralis superior, nucleus raphe dorsalis, nuclei linearis intermedius and linearis rostralis. Some scientists chose to group the linearis nuclei into one nucleus, shrinking the number of raphe to seven, e.g., NeuroNames makes the following ordering:

  Raphe nuclei of medulla
      Nucleus raphe obscurus (nucleus raphe obscurus) (B2 in Naidich)
      Nucleus raphe magnus (raphe magnus) (B3 in Naidich)
      Nucleus pallidus (raphe pallidus) (B1 in Naidich)
  Raphe nuclei of the pontine reticular formation
      Pontine raphe nucleus (raphe pontis) (B5 in Naidich)
      Inferior central nucleus (not in Naidich)
  Raphe nuclei of the midbrain reticular formation
      Superior central nucleus (nucleus centralis superior)(B6, B8 in Naidich)
      Dorsal raphe nucleus (nucleus raphe dorsalis)(B7 in Naidich)

Image and Location

Neurosynth structure image:

Neurosynth connectivity image:

(Woo et al. 2009)

IV, fourth ventricle; ACh, acetylcholine; CGRP, calcitonin gene-related peptide; LC, locus coeruleus; PAG, periaqueductal grey region; MRN, magnus raphe nucleus; NKA, neurokinin A; NO, nitric oxide; SP, substance P; SPG, superior sphenopalatine ganglion; SSN, superior salivatory nucleus; TG, trigeminal ganglion; TNC, trigeminal nucleus pars caudalis; VIP, vasoactive intestinal peptide. (Pietrobon et al. 2003)

Searches

Searches so far:

word [search_in] and/or/not_operators word [all] e.g., RVM [all] and Fields [author]

Most important references

(classic papers, best papers) APA 5th format from Endnote, e.g.,

Fields, H. L. (2000). Pain modulation: expectation, opioid analgesia and virtual pain.Progress in brain research, 122, 245-253.

Structure

(from Wikipedia)

The nucleus raphes magnus, located directly rostral to the nucleus raphes obscurus, is afferently stimulated from axons in the spinal cord and cerebellum. This makes the nucleus raphes magnus a likely candidate for part of the motor system; however, it seems to participate in the endogenous analgesia system. Mounting evidence suggests that the nucleus raphes magnus plays an important role in homeostatic regulation.

The nucleus raphes magnus receives descending afferents from the periaqueductal gray, the paraventricular hypothalamic nucleus, central nucleus of the amygdala, lateral hypothalamic area, parvocellular reticular nucleus and the prelimbic, infralimbic, medial and lateral precentral cortices.

All of these brain areas influence the main function of the nucleus raphes magnus. The main function of the nucleus raphes magnus is mostly pain mediation; in fact it sends projections to the dorsal horn of the spinal cord to directly inhibit pain. The nucleus raphes magnus releases enkephalin when stimulated. The periaqueductal gray, the epicenter of analgesia, sends efferent connections to the nucleus raphes magnus in when it is stimulated by opiates (endogenous or otherwise).

All of this seems to indicate that the nucleus raphes magnus is part of the endogenous opiate system, and acts to inhibit pain in the spinal cord.

Inputs

Name, and code Strength (L, M, H), Confidence (L, M, H), Transmitter(s)

Outputs

Name, and code Strength (L, M, H), Confidence (L, M, H), Transmitter(s)

Functions

Summary list

Function Area 1 [Name]

Effects of stimulation

Electrical stimulation of the PAG produces analgesia, as well as administration of morphine to the PAG or nucleus raphes magnus. The antinociceptic effects of electrical stimulation of the PAG can be blocked by administering naloxone, an opiate antagonist, to the nucleus raphes magnus.

This work compares the effects of electrical stimulation of the paraventricular hypothalamic nucleus (PVN) and the raphe magnus nucleus (RMg) on the single-unit response from dorsal spinal cord neurons activated by nociceptive receptive field stimulation. We evaluated the effects of stimulating the PVN or RMg individually or simultaneously, as well as PVN stimulation after RMg electrolytic lesion. PVN or RMg stimulation suppressed the A-delta, C fiber, and postdischarge, and we demonstrated that their simultaneous stimulation increases the duration and intensity of suppressive effects. RMg lesion increased the peripheral responses, but PVN stimulation continued to be suppressive. The intrathecal administration of 20 μl of a 10⁻⁵ M solution of a specific oxytocin antagonist strongly reduced the PVN effects, and 20 μl of 10⁻⁶ M naloxone significantly reduced the RMg suppression of receptive field responses. Some spinal cord cells presented a short-latency, evoked action potential (6.8 ms and a variability of ±0.5 ms) produced by the RMg stimulation. This is interpreted as a direct postsynaptic action of the RMg on the spinal cord cells. We never found similar responses produced by the PVN, and therefore, we propose that the PVN effects are presynaptic. Finally, the immunohistochemical experiments confirmed the oxytocinergic and the vasopresinergic innervation used by the PVN projection to the RMg, and they raise the possibility that other neurotransmitters are involved. We conclude that the PVN and the RMg form part of a homeostatic analgesic mechanism acting on the same spinal cord cells to block the noxious information, but using different mechanisms. Both structures, and others, contribute to the homeostatic mechanism of endogenous analgesia. Condés-Lara M, Rojas-Piloni G, Martínez-Lorenzana G, Diez-Martínez DC, Rodríguez-Jiménez J. Functional interactions between the paraventricular hypothalamic nucleus and raphe magnus. A comparative study of an integrated homeostatic analgesic mechanism.Neuroscience. 2012 May 3;209:196-207. Epub 2012 Feb 22.

Effects of lesions/inactivation

  • List with references.
  • Unordered List Item

Effects of microinjection

  • List with references.
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Optogenetics

  • List with references.
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Depuy, S.D., Kanbar, R., Coates, M.B., Stornetta, R.L., and Guyenet, P.G. (2011). Control of breathing by raphe obscurus serotonergic neurons in mice. J. Neurosci. 31, 1981–1990.

Other

Function Area 2 [Name]

Effects of stimulation

Effects of lesions/inactivation

  • List with references.
  • Unordered List Item

Effects of microinjection

  • List with references.
  • Unordered List Item

Optogenetics

  • List with references.
  • Unordered List Item

Other

Studies activating

Coordinates

Coordinates (x, y, z): [0, 0, 0] , [0, 0, 0] Say how overall coordinates were derived here (single study? average? structural landmark?)

Specific study coordinates (if not too many)

(not sure if these are correct, need to check my “method” with someone)

Study Description x y z
Evans 2009 Ran. num. gen. > rest 2 -25 -43
1st Author Name 20xx Contrast Descrip 0 0 0
1st Author Name 20xx Contrast Descrip 0 0 0

List of Studies

Specific, key studies

Study list: Coordinate based

Neurosynth results for coordinate(s)

<list studies here from Neurosynth database>

Last modified: 2017/05/13 02:15