(A and B) Polar plots of the post-stimulus effects (PStEs) for Facilitation, Suppression, and background electromyogram (EMG) at four different current intensities during the hold period for the eight peripheral targets. Vertical bars next to the polar plots show the magnitudes of PStEs or background EMGs. (A) Responses in the palmaris longus (PL) muscle at current intensities of 70 μA, 180 μA, 1000 μA, and 1700 μA through Elec. No. 3. (B) Responses in the flexor digitorum profundus (FDP) muscle by stimulation at current intensities of 70 μA, 200 μA, 1000 μA, and 1700 μA through Elec. No. 3. (C) Effect of current intensity on output type for PStEs. Facilitation, only Facilitation in all targets; Suppression, only Suppression in all targets; Facilitation+ and Suppression, stimulations induced both PStEs, and larger magnitudes of Facilitation than Suppression; Facilitation and Suppression+, stimulations induced both PStEs and larger magnitudes of Suppression than Facilitation; No response, no PStEs in all targets. (D) Mean values and SEs for the magnitudes of PStEs calculated in each current intensity. Statistics: one-way factorial ANOVA with Tukey-Kramer correction for post hoc multiple comparison (*, p<0.05; **, p<0.01; ***, p<0.001). (E and F) Population data of effect of current intensity on (E) Spinal PD and (F) Normalized Spinal PD. Red or blue thick lines indicate circular medians and significant nonuniform distributions (Rayleigh test, p<0.05) toward its direction (v-test; *, p<0.05; **, p<0.01; ***, p<0.001). Normalized Spinal PDs for Facilitation and Suppression evoked by lower (<1350 μA) intensity stimulation were significantly nonuniform (Rayleigh test, p<0.05) around 0° (v-test; *, p<0.05; **, p<0.01; ***, p<0.001), whereas Normalized Spinal PDs for Facilitation evoked by high intensity stimulation (≥1350 μA) was significantly nonuniform (Rayleigh test, p<0.05) around 180° (v-test; *, p<0.05; **, p<0.01; ***, p<0.001). Horizontal bars below each polar plot show the number of muscular conditions.