The effect of gestational ethanol exposure on stimulus-induced sensory activity in the trigeminal/somatosensory system was determined. The mature offspring of mothers fed an ethanol-containing diet (Et) or pair-fed a nutritionally matched control diet (Ct) were examined. The C-row mystacial whiskers were stimulated. Glucose utilization in the principal sensory nucleus of the trigeminal nerve (PSN), ventrobasal thalamus, and somatosensory cortex was determined with [14C]2-deoxyglucose autoradiography. In Ct- and Et-treated rats, whisker stimulation increased glucose utilization in C-row barrel(oid)s in the left PSN, the right ventrobasal thalamus, and the right somatosensory cortex. The rate of glucose utilization in the C-row barrel(oid)s and in nonstimulated regions was lower in the Et-treated rats than in controls. In the cortices of Ct-treated rats, the activity in the C-row barrels on the right side was greater than in the right nonbarrel somatosensory cortex. Et-treated rats also exhibited an increase in glucose utilization, albeit smaller than that in the Ct-treated rats. In contrast, the glucose utilization in the left B- and C-row barrels of Ct-treated rats was decreased. No such decrease was evident in the left cortices of Et-treated rats. Thus, stroking whiskers stimulates the activity of sites in the trigeminal/somatosensory system. In cortex, the definition of these sites is emphasized by depressed activity, i.e., "surround" inhibition, in sites connected via callosal or corticocortical projections. Prenatal exposure to ethanol depresses the metabolic activity regardless of the physiological state; however, the "surround" inhibition of cortical activity is eliminated by prenatal exposure to ethanol through an exuberant projection.