Depression is one of the most common psychiatric disorders with about one third of patients being considered treatment-resistant. Various neuromodulation approaches have been explored, including deep brain stimulation (DBS) of the medial forebrain bundle (mfb), which has shown promising results in clinical studies. In recent years transcranial focused ultrasound (FUS) at low intensities has been emerging as another form of stimulation. However, challenges arise from skull absorption, necessitating lower frequencies and therefore resolutions.To address this, we report on the first steps in a collaborative project (UPSIDE), aiming to develop an epidural FUS chip. Paired with an innovative epidural recording electrode based on an ion-gated organic electrochemical transistor (IGT), we aim for the development of a closed-loop system to be tested in the Flinders Sensitive Line (FSL) rodent depression model.In this initial phase, electrocorticogram recordings with novel IGT based high-density probe, as well as the recording of local field potentials was performed in FSLs, to look at the response to mfb DBS. Animals showed an increase in low gamma activity compared to controls in the Nucleus accumbens, Ventral Tegmental Area and to some extent the prefrontal cortex.For an eventual mfb stimulation with FUS, optimal parameters for the epidural application are determined through stimulation of rat brain slice cultures, coupled with cFos activation assessment in narcotized animals. These first steps contribute to a better understanding of the effects of FUS in general, as well as neuromodulation in depression.