Poster #: 114
Topic: Speech and language (incl. deficits)
Friday, Sep 11, 2015
Somatotopic semantic priming and prediction in the motor system
1Department of Philosophy and Humanities, Freie Universität Berlin, Berlin, Germany
2Department of Philosophy and Humanities, Freie Universität, Berlin, Germany
The recognition of action-related sounds and words activates motor regions and reflects the semantic grounding of these symbols in action information. Furthermore, modality-preferential motor cortex even exerts a causal influence on sound perception and language comprehension. However, proponents of classic symbolic theories dispute the motor system’s role in the semantic processing of meaningful stimuli, but attribute meaning to an amodal semantic system instead. To clarify whether the motor system carries genuine semantic processes, we used multi-channel event-related potentials (ERPs) to investigate priming effects manifest at the neurophysiological level between action sounds and spoken words semantically related to face or leg actions. To direct subjects’ attention away from the sounds, a distraction-oddball design was used and the mismatch negativity (MMN) to rare “deviant” mouth- and leg-related action words (“kiss” and “kick”) was recorded in the context of frequent “standard” mouth- or leg related-action sounds (“whistle”, “footstep”) or non-action meaningful sound (“water drop”). Event-related potentials revealed that action-related words produced significantly larger stimulus-evoked and predictive brain responses when presented in body-part-incongruent context (i.e., “kiss” in footstep sound context; “kick” in whistle context) than in body-part-congruent context, a pattern consistent with semantic priming. The main cortical generators of the semantic priming effect were localized in motor cortex and followed a somatotopic pattern. As our results show neurophysiological manifestations of semantic priming in the motor cortex, they prove genuine semantic processing in the motor system and thus semantic grounding in a modality-preferential system of the human brain.