median raphe nucleus
The median raphe nucleus (or superior central nucleus) is composed of polygonal, fusiform and pyriform neurons and exists rostral to the nucleus raphe pontis. One trait of the MRN is its inhibition by lysergic acid diethylamide and psilocin, two serotonin antagonist hallucinogens. The inactivation of the nucleus centralis superior via LSD produces a dose dependent inactivation in the MRN, but not in the raphe pallidus[WP,unvetted].