RESPONSES OF NEURONS IN THE CAUDAL INTRALAMINAR THALAMIC COMPLEX OF THE RAT TO STIMULATION OF THE UTERUS, VAGINA, CERVIX, COLON AND SKIN

This study examined responses of 35 neurons in the caudal intralaminar (IL) thalamic nuclei in 12 adult female virgin rats to mechanical sti mulation of the skin (brush, pressure, pinch) and to 4 different visce ral stimuli (noxious distension of the uterine horns and vaginal canal ; gentle distension of the colon and probing the cervix). As in male r ats and other species, many IL neurons (24/35) responded to frankly no xious somatic stimuli applied to several bodily regions. Some of these (16/24) also responded to one or more of the visceral stimuli (mainly the noxious ones), while 4/35 responded only to a visceral stimulus. Thus, unlike neurons in lateral thalamus studied under identical condi tions, IL neurons appear to be signalling information primarily when i ntense somatic and visceral stimuli are frankly above the noxious thre shold.