Stimulus waveforms for selective neural stimulation

The authors review recent efforts to design stimulus waveforms for selective electrical stimulation of the nervous system. Two types of selectivity are considered. Fiber diameter selectivity refers to the ability to activate one group of nerve fibers having a common diameter without activating nerve fibers having different diameters. Spatial selectivity refers to the ability to activate nerve fibers in a localized region without activating nerve fibers in neighboring regions. The fundamental principles governing the response of excitable nerve fibers to imposed stimuli are reviewed and used to design waveforms. The emphasis of the presentation is on excitation of peripheral myelinated nerve fibers, The underlying principles, however, are broadly applicable to all excitable membranes