Ungar I J, Mortimer J T, Sweeney J D
Ann Biomed Eng. 1986;14(5):437-50. doi: 10.1007/BF02367364.
Unidirectionally propagating action potentials, which can be used to implement transmission failure on peripheral nerve through "collision block," have been generated electrically on cat myelinated peripheral nerve using a monopolar electrode cuff with the conductor positioned closest to the "arrest" end of the cuff. A single cathode located at least 5 mm from the arrest end resulted in unidirectional propagation with minimal current and charge injection. The range of stimulus current values that produced unidirectional propagation increased with increases in longitudinal asymmetry of cathode placement over the range of asymmetries tested (1.7:1 to 7:1). The stimulus current pulse that minimized charge injection was quasitrapezoidal in shape with a plateau pulse width of approximately 350 microseconds and an exponential trailing phase having a fall time (90%-10%) of approximately 600 microseconds These parameters were found to be independent of cuff geometry. Arrest efficiency was not degraded using a cuff of sufficient internal diameter to prevent nerve compression in chronic implantation. The critical current density within the extracellular space of the electrode cuff required to produce conduction failure at the arrest end was estimated to be 0.47 +/- 0.08 mA/mm2.
单向传播的动作电位可通过“碰撞阻断”实现外周神经的传导阻断，利用单极电极套在猫的有髓外周神经上已成功电产生了这种电位，电极套的导体放置在最靠近套的“阻断”端处。位于距阻断端至少5毫米处的单个阴极可实现单向传播，且电流和电荷注入最小。在所测试的不对称范围（1.7:1至7:1）内，随着阴极放置纵向不对称性的增加，产生单向传播的刺激电流值范围也增大。使电荷注入最小化的刺激电流脉冲呈准梯形，平台脉冲宽度约为350微秒，指数下降相的下降时间（90%-10%）约为600微秒，这些参数与电极套几何形状无关。使用内径足够大以防止慢性植入时神经受压的电极套，阻断效率不会降低。估计在电极套细胞外空间产生阻断端传导失败所需的临界电流密度为0.47±0.08 mA/mm²。
