The locus of electrically excitable tissue where action potentials are induced can be controlled using the physiological principle of electrotonus. A first pulse having a first amplitude and a first pulse width is applied to a first electrode adapted to be adjacent the tissue to generate a first subthreshold...http://www.google.ca/patents/US5925070?utm_source=gb-gplus-sharePatent US5925070 - Techniques for adjusting the locus of excitation of electrically excitable tissue
