Electroconvulsive therapy (ECT) is the 1st electrical brain-stimulation treatment. It was developed to treat the severe forms of depression that are not irresponsive to medication. However, it is likely to cause massive convulsions, so it is less used today.
Transcranial magnetic stimulation (TMS) is a non-invasive alternative technique to ECT. It uses magnetic stimulation instead of electric stimulation, it is an FDA (food and drug administration) approved treatment for depression.
Thus, the blank can be filled with transcranial magnetic stimulation.