THE EFFECT OF STIMULUS PULSE DURATION ON SELECTIVITY OF NEURAL STIMULATION

Choice of stimulus parameters is an important consideration in the des ign of neural prosthetic systems. The objective of this study was to d etermine the effect of rectangular stimulus pulsewidth (PW) on the sel ectivity of peripheral nerve stimulation. Computer simulations using a cable model of a mammalian myelinated nerve fiber indicated that shor ter PW's increased the difference between the threshold currents of fi bers lying at different distances from an electrode, Experimental meas urements of joint torque generated by peripheral nerve stimulation dem onstrated that shorter PW's generated larger torques before spillover and created a larger dynamic range of currents between threshold and s pillover. Thus, shorter PW's allowed more spatially selective stimulat ion of nerve fibers, Analysis of the response of a passive cable model to different duration stimuli indicated that PW dependent contributio ns of distributed sources to membrane polarization accounted for the o bserved differences in selectivity.