When a motor task resembles a linguistic task: the contribution of the N400 ERP effect

The embodied cognition theories showed the relationship between the linguistic system and the motor system; by revealing a strength connection between the motor and language brain areas during a linguistic task that implicates a motor representation. In the present work we focalized the “inverse” side of the equation: language = motor, i.e. motor = language activation. During the experiments subjects performed two different tasks in which they saw a sequence of four images that represented an action directed toward an object. The subjects had to respond if the object represented in the sequence was correctly or incorrectly used. In the Experiment 1 the object may be used in an appropriate or inappropriate manner; in the Experiment 2 the object may be contextually adequate or inadequate. 20 subjects participated to the two experiments and ERP measures were recorded in order to detect the presence of a specific cortical linguistic marker, the N400, generally related to the processing of anomalous semantic information in linguistic domain. The data were analyzed using repeated measures ANOVA, with three independent factors: condition (correct or incorrect action); cortical area (frontal, frontal-central, parietal, temporal, occipital area) and side (left and right). A significant main effect for N400 in case of an incorrect condition in the Fz cortical site was found, which indicates a higher brain activation within the dorsolateral frontal cortex. The main conclusion of the present research pointed out the presence of the N400 index, previously found in response to the linguistic tasks when the subject reveals the perception of semantic anomaly, that was also observed in motor tasks when the subject is required to judge the semantic significance of a motor action in case of an anomalous information. Thus the resemblance between the two domains, linguistic and motor respectively, was elucidated.