Increased intensity perception of aversive taste following right anteromedial temporal lobe removal in humans

We used a modified version of the Spatial Taste Test to assess taste intens ity perception in patients with either left or right temporal resection fro m the anteromedial temporal lobe (AMTL), and a group of control subjects. S weet, sour, salty and bitter solutions were applied onto discrete locations of the tongue to stimulate either left or right fungiform, or left or righ t foliate papillae. Intensity ratings were assessed with the Labeled Magnit ude Scale. Subjects also sipped 5 ml of each solution for whole mouth stimu lation. Genetically based determinants of taste sensitivity were assessed w ith ratings of 6-n-propylthiouracil, and covaried from all analyses. As in previous studies, analysis of covariance indicated that the subjects in the right temporal group rated an aversive bitter taste as more intense than d id subjects in the control group. In contrast, there were no group differen ces for sucrose ratings, suggesting that the AMTL may be involved preferent ially in processing aversive compared with hedonic tastes. No group x side, or group x location effects were present. These results confirm that remov al of the right AMTL in humans results in increased taste intensity/aversiv eness perception. This finding complements existing literature indicating t hat the AMTL is important for processing aversive taste, and suggests that inhibitory mechanisms may play an important role in such processing.