The Effect on Reaction to Painful Stimuli of Lesions in the Centromedian Nucleus in the Thalamus of the Monkey

Abstract

Evidence has accumulated indicating that the centromedian nucleus of the thalamus participates in an organism's reaction to noxious stimuli. The purpose of the present study was to determine whether or not the centromedian nucleus is involved in the monkey's reaction to electric shock. Results indicated that lesions of sufficient size (larger than 40%) produce a significant (p <.01) effect on shock-escape threshold in the monkey. It is proposed that the centromedian nucleus is part of an ‘orbital system’ extending from the orbital prefrontal cortex, through the ventral caudate and medial pallidum, to the thalamus; and that one of the functions of this system is to modulate reaction to painful stimuli.