After A afferent fibers are blocked by DC cur-rent,N_1, N_2 and P_1 waves disappear,leaving only the P_2 wave which disappearsonly when C potential is abolished.

• 用直流电阻断 A 类传入仅保留 C波时,N_1、N_2、P_1波消失而 P_2波仍存在,加大阻断电流使 C 波消失时,P_2波随之消失。