Reading salt activates gustatory brain regions: fMRI evidence for semantic grounding in a novel sensory modality

Abstract

Because many words are typically used in the context of their referent objects and actions, distributed cortical circuits for these words may bind information about their form with perceptual and motor aspects of their meaning. Previous work has demonstrated such semantic grounding for sensorimotor, visual, auditory, and olfactory knowledge linked to words, which is manifest in activation of the corresponding areas of the cortex. Here, we explore the brain basis of gustatory semantic links of words whose meaning is primarily related to taste. In a blocked functional magnetic resonance imaging design, Spanish taste words and control words matched for a range of factors (including valence, arousal, image-ability, frequency of use, number of letters and syllables) were presented to 59 right-handed participants in a passive reading task. Whereas all the words activated the left inferior frontal (BA44/45) and the posterior middle and superior temporal gyri (BA21/22), taste-related words produced a significantly stronger activation in these same areas and also in the anterior insula, frontal operculum, lateral orbitofrontal gyrus, and thalamus among others. As these areas comprise primary and secondary gustatory cortices, we conclude that the meaning of taste words is grounded in distributed cortical circuits reaching into areas that process taste sensations.

Figure 1.

Brain activation when comparing the taste word versus the control word conditions (A) and the control word versus the baseline conditions (B) at the threshold (P < 0.01, FDR-corrected at the single voxel level and P < 0.05, Familywise Error-corrected at the cluster level). Color bars represent the T-values scale for each contrast. Left is left in all the brain images. (C) Represents percentage signal change in brain local maxima for those regions showing higher activation when comparing the TW versus CW conditions. ACC, anterior cingulated cortex; AG, angular gyrus; CW, control words; FG, fusiform gyrus; FO, frontal operculum; IFC, inferior frontal cortex; lOFC, lateral orbitofrontal cortex; MTC, middle temporal cortex; PC, posterior cingulate; PCG, precentral gyrus; PMC, premotor cortex; Pt, putamen; SMA, supplementary motor area; SMFC, superior/middle frontal cortex; SN, substantia nigra; SPFC, superior prefrontal cortex; STN, subthalamic nucleus; TW, tasty words.