Perception of odor-induced tastes following insular cortex lesion

Lesions of the insula can affect olfaction and gustation. Here, we examined the effect of insula lesions on taste and taste-like experiences generated via smelling (i.e., odor-induced tastes) in patients with focal insula lesions and intact olfaction. From a set of 16 patients with lesions to the insula, we found 7 (6 with right-sided lesions) who performed normally on various olfactory measures. These were compared to 42 normal control subjects on tests of gustatory and odor-induced taste perception as well as control measures. The patients were impaired relative to controls on most gustatory measures. They were also impaired on tests of odor-induced taste perception, primarily for stimuli presented on the left side. Examining cases individually revealed evidence of a dissociation: two patients exhibited no impairment in odor-induced taste perception in spite of gustatory deficits. Together, these findings suggest that the insula mediates taste recognition, hedonics, and intensity judgments as well as odor-induced taste perception. However, the areas responsible for aspects of taste perception and those responsible for odor-induced taste do not fully overlap each other and they are also independent of olfactory areas.