A system, comprising: an electrode arrangement; a neuromodulation generator configured to use electrodes in the electrode arrangement to generate modulation fields including: a first modulation field over a test region of neural tissue along the electrode arrangement to prime the neural tissue throughout the test region; and a second modulation field to test a plurality of targeted locations of neural tissue within the test region for therapeutic effectiveness, wherein the neural tissue to be tested by the second modulation field has been primed by the first modulation field; a memory configured to store a first modulation field parameter set for use to generate the first modulation field, and a second modulation field parameter set for use to generate the second modulation field to modulate one of the plurality of the targeted locations within the test region, the second modulation field parameter set including programmable fractionalized current values for electrodes within the electrode arrangement and being programmable to change the second modulation field to modulate other ones of the plurality of targeted locations, wherein modification of the programmable fractionalized current values moves the second modulation field; and a controller configured to control the neuromodulation generator to use the first modulation field parameter set to prime the test region with the first modulation field and to use the second modulation field parameter set to deliver a second modulation field to modulate the one of the targeted locations within the test region. an electrode arrangement; a neuromodulation generator configured to use electrodes in the electrode arrangement to generate modulation fields including: a first modulation field over a test region of neural tissue along the electrode arrangement to prime the neural tissue throughout the test region; and a second modulation field to test a plurality of targeted locations of neural tissue within the test region for therapeutic effectiveness, wherein the neural tissue to be tested by the second modulation field has been primed by the first modulation field; a first modulation field over a test region of neural tissue along the electrode arrangement to prime the neural tissue throughout the test region; and a second modulation field to test a plurality of targeted locations of neural tissue within the test region for therapeutic effectiveness, wherein the neural tissue to be tested by the second modulation field has been primed by the first modulation field; a memory configured to store a first modulation field parameter set for use to generate the first modulation field, and a second modulation field parameter set for use to generate the second modulation field to modulate one of the plurality of the targeted locations within the test region, the second modulation field parameter set including programmable fractionalized current values for electrodes within the electrode arrangement and being programmable to change the second modulation field to modulate other ones of the plurality of targeted locations, wherein modification of the programmable fractionalized current values moves the second modulation field; and a controller configured to control the neuromodulation generator to use the first modulation field parameter set to prime the test region with the first modulation field and to use the second modulation field parameter set to deliver a second modulation field to modulate the one of the targeted locations within the test region. <EOS>