Transcranial direct current stimulation (tDCS) is a clinical technique employed in the treatment of multiple pathological conditions such as chronic pain, stroke, and among others. Nonetheless, a comprehensive exploration of the impact of electric fields on cortical circuits is still necessary. Studies by Frohlich and McCormick (2010) and D’Andola et al. (2018) have revealed the effect of direct current (DC) exogenous fields to modulate emergent activity patterns in cortical slices exhibiting spontaneous slow oscillations (SO).Considering the potential of tDCS as a treatment option for epilepsy, we investigated the effects of DC fields on SO, pre-epileptic, and epileptiform cortical activities in cortical slices in vitro. We applied a homogeneous electric field (EF) perpendicular to cortical layers. Exogenous electric currents ranging from -500 to +500 µA, were applied after administration of GABAA receptors antagonist, bicuculline methiodide, at concentrations of 1 µM and 4 µM.To have a direct measure of the applied electric fields and to investigate as well the infraslow components of the resulting effects, we used graphene-based solution-gated field-effect transistors (gSGFETs) that record the brain's complete signal spectrum (Cancino-Fuentes et al, 2024). Our study quantifies the applied fields and finds that negative fields with intensities exceeding 300uA exhibit promising potential not only in blocking epileptic events but also in inducing a frequency akin to the baseline frequency of SO.Our results contribute to a deeper understanding of cortical dynamics and to potential advancements in neuromodulation techniques and epilepsy treatment.Funding: CORTICOMOD PID2020-112947RB-I00, was financed by MCIN/AEI/10.13039/501100011033