Shared mechanisms of tDCS, tACS, Temporal Interference Stimulation, and ECT

Shared mechanisms of transcranial Direct Current Stimulation (tDCS), transcranial Alternating Current Stimulation (tACS), Temporal Interference (TI) Stimulation, and Electroconvulsive Therapy (ECT).
Talk by Marom Bikson
What do these seemingly very different non-invasive electrical brain stimulation techniques have in common in regard to mechanism?
Includes finite-element-method (FEM) "Adaptive" model of head current flow during brain stimulation. Brain slice models. Oscillations.