Full title: The role of the left DLPFC in endogenous task preparation: an experimental repetitive Transcranial Magnetic Stimulation study Running head: Cognitive effects of rTMS of the left DLPFC

The precise role of the Dorsolateral Prefrontal Cortex (DLPFC) in attentional set activation is still not entirely clear. Hence, repetitive Transcranial Magnetic Stimulation (rTMS) can be applied to interfere with neural processing to determine whether a specific brain area is required in task performance. In this study, the influence of one session of High Frequency (HF)-rTMS of the left DLPFC on a reaction task using visual and auditory trials was investigated. Participants were instructed to pay constant attention to the visual stimuli, whereas they were informed that distracting auditory stimuli could also appear. Participants had to respond to both stimuli. Results indicate that after one session of HF-rTMS of the left DLPFC, performance was improved for the primary task, but not for the distracters. Specifically, we found decreased RT for an endogenous component of attentional control which embodies the online representations of task relevant information. To conclude, the current results highlight a specific role of the left DLPFC in actively preparing for a specific task in the presence of a distracting task.