Modeling study on selective activation of small mammalian nerve fibers using asymmetric biphasic pulses with a monopolar point electrode

The aim of this study is to investigate theoretically the possibility for activation of small mammalian myelinated nerve fibers without activating larger ones when stimulating a fiber bundle with a monopolar point electrode using biphasic pulses, which can reduce the electrochemical damage resulted from stimulation pulses to nerve fibers. A simulation system for studying the electrical properties of mammalian myelinated nerve fibers was built based on a simple infinite and homogeneous volume conductor model. By use of an asymmetric but charge-balanced stimulation waveform, the sensitivity of excitation and blocking threshold of nerve fibers to fiber diameter, electrode-fiber distance was calculated. The results show that selective activation of small mammalian myelinated fibers may be possible in a region at some distance from the electrode using biphasic pulses.