Multi-phasic fields are produced at a neuromodulation site using electrodes. A first phase is directed at a target region such that a first-polarity electrical charge is injected to the target region, and a second phase is directed at portions of the neuromodulation site other than the target region, such that a second-polarity electrical charge opposite the first-polarity electrical charge is injected to those portions of the neuromodulation site to essentially neutralize the first-polarity charge injected at the neuromodulation site while maintaining at least a portion of the first-polarity charge at the target region. In some embodiments, each anode used to produce the first phase is used as a cathode to produce the second phase, and each cathode used to produce the first phase is used as an anode to produce the second phase, and the quantity of charge injected by each electrode in both phases is essentially zero.
Locally-polarized and globally unpolarized neuromodulation system and method