The median raphe nucleus (MRN) (also known as the nucleus raphes medianus (NRM) or superior central nucleus) is composed of polygonal, fusiform and piriform neurons and exists rostral to the nucleus raphes pontis.
Inhibition of the MRN in cats by lysergic acid diethylamide (LSD) and psilocin, two serotonin antagonist hallucinogens, leads to dose dependent behavioral changes, indicating the MRN may be an important site of action for humans hallucinations.
See also 
- ^ Trulson, M.E., Preussler DW and Trulson V.M. Differential effects of hallucinogenic drugs on the activity of serotonin-containing neurons in the nucleus centralis superior and nucleus raphe pallidus in free-moving cats. American Society for Pharmacology and Experimental Therapeutics Volume 228, Issue 1, pp. 94-102, 1 January 1984