Taste and odour-induced taste perception following unilateral lesions to the anteromedial temporal lobe and the orbitofrontal cortex.

Odour-induced tastes occur when smelling certain odours (e.g., sweet-smelling vanilla) and may represent a universal form of synaesthesia. If odour-induced tastes are perceptually akin to tastes generated by stimulating taste receptors on the tongue, as perceptual data imply, then these two forms of gustatory experience may also share common processing resources in the brain. In this study, we examine this hypothesis for two secondary gustatory processing areas--the orbitofrontal cortex (OFC) and amygdala. We compared nine patients with anteromedial temporal lobe (AMTL) resections that included the amygdala, and three patients with OFC damage, to a healthy comparison group (n = 42), on tests of olfactory, gustatory, and odour-induced taste perception. While AMTL patients had a range of generally small taste impairments, they were unimpaired on tests of odour-induced taste perception. Two of the three OFC cases had impairments in taste hedonics and discrimination. The case with the most profound gustatory deficit was also mildly impaired on tests of odour-induced taste perception. The OFC findings are consistent with overlaps in circuits supporting taste and odour-induced taste perception, especially those responsible for more perceptual aspects of processing.