Exp Brain Res (2011) 211:243–250 DOI 10.1007/s00221-011-2678-z 123 RESEARCH ARTICLE Modulation of the motor system during visual and auditory language processing Ludovica Labruna · Miguel Fernández-del-Olmo · Ayelet Landau · Julie Duqué · Richard B. Ivry Received: 2 July 2010 / Accepted: 1 April 2011 / Published online: 3 May 2011  Springer-Verlag 2011 Abstract Studies of embodied cognition have demon- strated the engagement of the motor system when people process action-related words and concepts. However, research using transcranial magnetic stimulation (TMS) to examine linguistic modulation in primary motor cortex has produced inconsistent results. Some studies report that action words produce an increase in corticospinal excitabil- ity; others, a decrease. Given the diVerences in methodol- ogy and modality, we re-examined this issue, comparing conditions in which participants either read or listened to the same set of action words. In separate blocks of trials, participants were presented with lists of words in the visual and auditory modality, and a TMS pulse was applied over left motor cortex, either 150 or 300 ms after the word onset. Motor evoked potentials (MEPs) elicited were larger fol- lowing the presentation of action words compared with control words. However, this eVect was only observed when the words were presented visually; no changes in MEPs were found when the words were presented auditorily. A review of the TMS literature on action word processing reveals a similar modality eVect on corticospinal excitability. We discuss diVerent hypotheses that might account for this diVerential modulation of action semantics by vision and audition. Keywords TMS · Language · Embodiment · Action · Reading · Listening · Visual · Auditory Introduction Action comprehension involves the engagement of neural regions traditionally associated with action production. The mirror neuron system (MNS), identiWed in physiological studies in non-human primates and fMRI studies with humans, spans premotor and parietal cortex (reviewed in Buccino et al. 2004; Morin and Grezes 2008). It has been shown that action representations within the MNS, exam- ined at either the single neuron or network level, can be activated through diVerent modalities. For example, cells in premotor cortex which are activated when a monkey reaches to pick up a peanut are also activated when the ani- mal observes the peanut being picked up by another agent (e.g., the experimenter) or when listening to the sound of a peanut shell being cracked (Kohler et al. 2002). Similarly, the MNS is not only activated when observing pictures or videos of actions, but also when participants listen to sounds related to these actions (Lahav et al. 2007; Pizzamiglio et al. 2005). This work suggests that units within the MNS represent the semantics of actions, and are not constrained by a spe- ciWc sensory context. Indeed, the functional domain of the MNS is thought to extend beyond action observation. Much of the excitement concerning these seminal observations L. Labruna (&) Health Science Department, University of Molise, Molise, Italy e-mail: lulabrun@gmail.com L. Labruna · A. Landau · R. B. Ivry Department of Psychology, University of California, Berkeley, CA, USA M. Fernández-del-Olmo Departamento de Educación Física e Deportiva, Facultade de Ciencias do Deporte e a Educación Física, INEF, Galicia, Spain J. Duqué Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve, Belgium