Reading taste metaphors recruits brain regions associated with taste processing

1. Reading taste metaphors recruits brain regions associated with taste processing Francesca M.M. Citron1,3, Evgeniya Kirilina2 & Adele E. Goldberg3,1 1Cluster of Excellence “Languages of Emotion”, Freie Universität Berlin, 2Dahlem Institute for the Neuroimaging of Emotion, Freie Universität Berlin, 3Linguistics Program, Princeton University, NJ Results (a) (b) Embodied metaphors Conceptual knowledge is represented in modal systems derived from perception (Barsalou, 1999). Abstract knowledge is represented by means of associations with concrete domains (Lakoff & Johnson, 1980) that are grounded in somato-sensory representations (Pulvermueller, 1999). For example, reading idioms that contain action words or texture metaphors recruits sensory-motor and texture-related brain regions, respectively (Boulenger et al., 2009; Lacey et al., 2012). What about taste metaphors? Given the paucity of neuroimaging studies supporting an embodied account, we decided to investigate this domain. (c) Figure 1. Main clusters of activation for the contrast metaphors > literal sentences. FEW- correction was applied at the cluster level. (a) The left frontal cluster, including the lateral OFC (MNI coordinates -42 21 -15; BA 11); (b) The frontal operculum (MNI -42 21 -15, BA 47), also included in the left frontal cluster of activation; Our Taste Metaphors 37 German metaphorical sentences and 37 literal counterparts, matched for length, frequency, familiarity, imageability, emotional valence and arousal, presented in written form. A priori ROIs confirmed involvement of left primary and secondary gustatory cortices for metaphors > literal sentences and for single taste words > non-taste words. No activations in the opposite contrasts (for either literal sentences or non-taste words) were found. Prediction: comprehension of taste metaphors will activate primary and secondary gustatory areas, i.e., lateral orbito-frontal cortex (lOCF), frontal operculum and anterior insula (AIC) more strongly than literal sentences. To make sure these predicted activations are due to taste and not metaphoricity per se, we presented all critical words in isolation at the end of experiment, e.g., “sweet” in isolation will refer to the actual taste and not to kindness. Methods • Participants: 26 native German speakers (M 27 years, SD 5; 19 women) • Task: Silent reading with occasional comprehension questions on filler trials; 2 runs with sentences, 1 final run with single words • fMRI parameters: • 3-Tesla scanner, 32-channel head matrix coil, TR 2.5 sec • 5 different TE (7.4; 17.2; 27; 37; 47 ms) to optimise detection of OFC • 37 slices per volume • Stimulus order and timings were optimised with OPTSEQ2 (Dale, 1999) • Each sentence was presented for 4 sec, each word for 1.5 sec • Baseline: (sequences of) hash mark strings ## ######## ##### • Total duration: about an hour; each of the 3 runs lasted about 8 min • Magnitude and phase images (field map) as well as T1 were acquired • SPM8 was used for data analysis • Contrasts between metaphors and literal sentences in both directions were performed as well as between taste and non-taste single words • Full-brain analyses; a priori region of interest (ROI) analyses on lOFC, frontal operculum and AIC; post-hoc ROI analyses on the amygdala Discussion Study 1 - Results The involvement of primary and secondary gustatory cortices during processing of taste metaphors compared with their literal counterparts supports the idea that abstract, metaphorical concepts are grounded in sensory-motor/perceptual representations. The same areas were active in response to single, taste-related words, e.g., sweet, biter, salty, compared with non-taste related words, e.g., nice, bad, expensive, confirming that these activations are due to taste and not metaphoricity. These results are in line with similar findings on action and texture metaphors (Boulenger et al., 2009; Lacey et al., 2012) as well as on single, taste-related words (Barros-Loscertales et al., 2012), and extend them to an additional source domain, namely taste. Boulenger, V., Hauk, O., & Pulvermueller, F. (2009). Grasping ideas with the motor system: Semantic somatotopy in idiom comprehension. Cerebral Cortex, 19, 1905-1914. Dale, A.M. (1999) Optimal experimental design for event-related fMRI. Human Brain Mapping, 8, 109-114. Lacey, S., Stilla, R., & Sathian, K. (2012) Metaphorically feeling: Comprehending textural metaphors anctivates somatosensory cortex. Brain and Language, 120, 416-421. Lakoff, G., & Johnson, M. (1980). Metaphors we live by. Chicago: University of Chicago. Pulvermueller, F. (1999) Words in the brain's language. Behavioral and Brain Sciences, 22, 253-336. References Barsalou, L.W. (1999) Perceptual symbol systems. Behavioral and Brain Sciences, 22, 577-660. Barros-Loscertales, A., et al., (2012) Reading sald activates gustatory brain regions: fMRI evidence for semantic grounding in a novel sensory modality. Cerebral Cortex, 22, 2554-2563.