The cortical contribution in response to sustained attention was explored in the present research by using brain stimulation. Thus, repetitive transcranial magnetic stimulation (rTMS) is a potent tool that can be used to modify activity of targeted cortical areas. The effect of this stimulation technique on attentional processes was explored in the present research, which focalized on the sustained attentional task (Stroop task). High-frequency (10 HZ) rTMS stimulation was induced on the left dorsolateral prefrontal cortex (DLPFC) when subjects performed the Stroop task. The 10 Hz stimulation was able to induce a temporary potentiation of the cortical responsiveness by improving the neuron polarization activity. One control condition was provided, in addition to the DLPFC stimulation, that is sham stimulation. Based on this evidence we supposed the rTMs stimulation may increase the subjects’ performance in terms of both accuracy (number of correct responses) and efficiency (reduced RTs) when DLPFC was stimulated. The statistical results showed a consistent increased ability to focalize and sustain the attentional behavior, with significant more correct responses and shorter RTs. The effect of the left DLPFC was compared with previous studies that used low-frequency stimulation (inhibition paradigm) or that applied the stimulation on the controlateral (right) hemisphere. Specifically, the control functions of a frontal network, which includes the DLPFC, were largely discussed.