Taste perception in patients with insular cortex lesions

Research on nonhuman primates suggests that the primary taste cortex in humans is located in the rostrodorsal insula. Qualitative and quantitative assessment of taste perception was performed on 6 patients with unilateral damage to the insula, 3 patients with brain damage outside the insula, and 11 age-matched, normal subjects. Each subject identified the quality and intensity of the gustatory stimuli applied separately to the left and right sides of the anterior tongue. Damage to the right insula produced ipsilateral taste recognition and intensity deficits. Damage to the left insula caused an ipsilateral deficit in taste intensity but a bilateral deficit in taste recognition. The unexpected deficit in the left-hemispheric stroke patients for taste recognition on the right side of the tongue suggests that taste information from both sides of the tongue passes through the left insula.