A method of applying a neural stimulus with an implanted electrode array involves applying a sequence of stimuli configured to yield a therapeutic effect while suppressing psychophysical side effects. The stimuli sequence is configured such that a first stimulus recruits a portion of the fibre 5 population, and a second stimulus is delivered within the refractory period following the first stimulus and the second stimulus being configured to recruit a further portion of the fibre population. Using an electrode array and suitable relative timing of the stimuli, ascending or descending volleys of evoked responses can be selectively synchronised or desynchronised to give directional control over responses evoked. Also, controlling a neural stimulus by applying a neural 10 stimulus, measuring an evoked neural response, comparing the measured neural response to a desired response, and altering one or more stimulus parameters. x 10-3 EXP3-1- PW=80gs, l=6mA - Ovine Spinal Cord Stimulus Second, longer response Initial, short -1 response Time (ms) F1 x 104 [Exp: 3-1] E3 Pulse Width: 80] ps -05 -2 -2. U 1 2 3 4 5 6 7 8 9 Time (ns) Figure 16
METHOD AND APPARATUS FOR APPLICATION OF A NEURAL STIMULUS