There is a major demand for alternative treatments for Major Depressive Disorder (MDD), as its main line of treatment, pharmacotherapy-based approaches, have limited effectiveness and low tolerability. A safe and effective home-based brain stimulation treatment would offer an accessible alternative to medications. Our objective was to develop a transcranial current stimulations (tCS) system that can provide an effective home-based treatment for MDD. To achieve that, we required:​ 1. an inexpensive solution for quick and accurate positioning of the stimulating electrodes, and 2. the ability to perform and adjust stimulation in real time.

First, we developed and tested a quick and accurate positioning method using 3D scanning and 3D printing. Test results show accurate and precise positioning compared to other standard positioning methods. Second, we developed and tested an algorithm that can extract phase and frequency estimates from brain recordings and control the stimulation in real-time. Third, we developed a closed-looped brain stimulation system based on transcranial pulsed current stimulation (tPCS) that can effectively phase-lock to a particular brain oscillation frequency. We tested this novel brain stimulation approach to study its effect on the Salience Network, which is associated with MDD and other neuropsychiatric disorders. The results from our clinical trial did not show modulation of brain activity using the novel brain stimulation technique. Alternative stimulation protocols and tasks should be considered in order to better understand the potential of phase-locked tPCS.

We achieved our objective of creating a solution to quickly and accurately position the stimulator, and a method to perform and adjust stimulation in real time. Furthermore, we were able to show that phase-locked tPCS does not show modulation of SN activity, as measured using established tasks and outcome measures. Future experimentation on phase-locked brain stimulation will help discover its potentials in helping MDD patients.