Bardi, L. & Mapelli, D.
Department of General Psychology, University of Padova, Padova, Italy
Response activation and selection in situations of conflict have been shown to recruit a large frontoparietal network. Within this network, a critical role in response selection has been attributed to premotor cortex. We applied single-pulse TMS over left and right premotor cortex (PM) at different timing after stimulus onset (SOAs) while participants were performing a spatial conflict task (the Simon task). In the Simon task a conflict arises because irrelevant spatial information competes for response selection either facilitating of interfering with performance. Responses are faster when stimulus and response position correspond than when they do not. Results showed that temporary interference with the left PM caused a suppression of the Simon effect due to a delay of corresponding trials in a early timing (160 ms SOA) while an increase of the Simon effect, due to a delay of non-corresponding trials, was observed in a later timing (250 ms SOA). These outcomes suggest that PM plays a critical role both in the activation of the corresponding response and in conflict resolution when the corresponding response has to be overcome. Moreover, our finding extends the idea of the left-hemisphere lateralization of the network for action selection in right-handed subjects.