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Neurophysiological distinction of action words in the fronto-central cortex



It has been suggested that the processing of action words referring to leg, arm, and face movements (e.g., to kick, to pick, to lick) leads to distinct patterns of neurophysiological activity. We addressed this issue using multi-channel EEG and beam-former estimates of distributed current sources within the head. The categories of leg-, arm-, and face-related words were carefully matched for important psycholinguistic factors, including word frequency, imageability, valence, and arousal, and evaluated in a behavioral study for their semantic associations. EEG was recorded from 64 scalp electrodes while stimuli were presented visually in a reading task. We applied a linear beam-former technique to obtain optimal estimates of the sources underlying the word-evoked potentials. These suggested differential activation in frontal areas of the cortex, including primary motor, pre-motor, and pre-frontal sites. Leg words activated dorsal fronto-parietal areas more strongly than face- or arm-related words, whereas face-words produced more activity at left inferior-frontal sites. In the right hemisphere, arm-words activated lateral-frontal areas. We interpret the findings in the framework of a neurobiological model of language and discuss the possible role of mirror neurons in the premotor cortex in language processing. Hum. Brain Mapp. 21:191–201, 2004. © 2004 Wiley-Liss, Inc.