Pulse responses of Pt/poly(3-hexylthiophene-2,5-diyl)/Polyethylene oxide + Mg(CF3SO3)(2)/Pt hetero-junction were studied, in which the weight modifications were calculated for the discharging and charging peaks, i.e., W-d and W-c, respectively. The responses were frequency selectivity depending significantly on two types of thresholds: one was the voltage threshold (V-th) leading to negative differential resistance in direct current properties. When the pulse amplitude was higher than Vth in a limited range, W-d was depressed at low-frequency stimulations and potentiated at high-frequency stimulations. However, W-c varied in a reverse trend, suggesting bi-directional signal transferring. The other was the frequency threshold (theta(m)) at which the responses turned from depression to potentiation for W-d. When the pulse amplitude was lower than Vth, no frequency selectivity was observed. Moreover, ionic contents influenced V-th and theta(m). High ion content enhanced Vth but reduced theta(m). Our study suggests to modulate frequency selectivity and signal transferring by controlling the two types of thresholds using ionic type and content. (C) 2016 Elsevier B.V. All rights reserved.