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From hand to mouth: Verb embodiment in action naming D.B. Den Ouden1, A. Baria1, J. Lee1, C.K. Thompson1,2 Aphasia and Neurolinguistics Research Laboratory, Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, United States/2Department of Neurology, Northwestern University, Chicago, IL, United States 1 Introduction: A growing body of research suggests that the conceptual representations of actions are partly grounded in motor representations and, therefore, rely on the motor cortex for processing (Pulvermüller, 2005). This embodiment theory further suggests that lesions to motor areas of the brain may lead to action-verb processing deficits in aphasia (Arévalo et al., 2007). Research on embodiment has typically considered verb processing, not production. In the present fMRI study, we investigated whether lexical retrieval of action verbs in overt speech production involves motor areas that are associated with these verbs. Methods: Fifteen right-handed native speakers of English (6 females; mean age 59 (33-69)) performed an action-verb naming task using 2 second video clips, to which they responded overtly with a single verb. Videos presented actions performed by one male actor in two conditions: ‘hand’ and ‘face’ actions. Verb items where matched for argument structure, lexical frequency, length in syllables and length in phonemes, and the videos where matched for visual complexity, i.e. the number and type of elements (objects, people) depicted, and showed both face and hand actions in full body view. Stimuli were presented in pseudorandom order (34 trials per condition), with a variable ISI (6-10 seconds). In separate runs, subjects also performed two motor tasks, for localization of hand (finger tapping) and face motor representations (sliding tongue behind teeth). Functional volumes with BOLD contrast were obtained on a 3T scanner. Data analysis was performed with SPM5 software, using the Marsbar tool for ROI analyses. Results: Based on the motor task activations, we determined the peak activation voxels for hand and face action execution for each individual subject on left and right hemisphere primary motor cortex (see Figure 1), sensorimotor cortex and premotor cortex. We drew 10 mm spheres around these peaks and used the resulting areas as ROIs for the analysis of verb naming. Contrast values for face and hand verbs were entered into a repeated measures 3x2x2x2 ANOVA, with the factors region, ROI type, hemisphere and verb type. This analysis revealed a main effect of region (F(2, 28) = 7.39, p<.05), driven by less overall activation in sensorimotor cortex than in the premotor and primary motor ROIs. Results also showed a main effect of ROI type (F(1,14) = 18.53, p<.05), driven by greater overall activation in the face areas than in the hand areas. Lastly, there was a significant interaction between verb type and ROI type (F(1,14) = 6.39, p<.05). Unexpectedly, however, this interaction was driven by higher activation of hand verbs in face areas and face verbs in hand areas, as shown in Figure 2. Conclusions: Greater activation in motor and premotor areas than in sensorimotor areas, as well as the greater overall activation in face areas, was to be expected, given the overt nature of the naming task. A suprising result, however, is the strong reversed embodiment effect, where hand action verbs show relatively higher recruitment of face areas than face action verbs, and vice versa. Implications of these data for the embodiment theory will be discussed. References: Arévalo, A (2007), 'Action and object processing in aphasia: From nouns and verbs to the effect of manipulability', Brain and Language, vol. 100, no. , pp. 79-94. Pulvermüller, F (2005), 'Brain mechanisms linking language and action', Nature Reviews Neuroscience, vol. 6, no. 7, pp. 576-582. Category: Language Sub-Category: Production