Dr. Marom Bikson, co-inventor of High-Definition tDCS (HD-tDCS), explains in simple and clear terms how HD-tDCS was invented and how it works. Starting with current flow models that showed conventional (sponge pad based) tDCS produced diffuse brain current flow, and then models of HD-tDCS that showed focal brain current flow. Along the way, High-Definition (HD) electrodes were invented, and the models were validated. 4x1 HD-tDCS can be as focal at Transcranial Magnetic Stimulation (TMS), while being portable low-power and wearable.

For more details on how to optimize HD-tDCS see this video:
   • Optimizing brain targeting with HD-tD...  

For more details on how tDCS (sub-threshold stimulation) works see this video:
   • Subthreshold Neuromodulation: How "lo...  

For a more technical and detailed look at HD-tDCS and models see this video:    • transcranial Electrical Stimulation (...