Figure 6
Simulation and in vivo comparison of monopolar and bipolar ring electrodes. (A) Maximum activating function (AF) along the DNP or CSN evoked by 1 mm and 2 mm monopolar and bipolar ring electrodes. The monopolar electrode configurations generated larger AFs than the bipolar configurations (†, p < 0.05, Bonferroni post-hoc comparison). (B) Selectivity and AF ratio for the 2 mm monopolar ring electrode compared to the 2 mm bipolar ring electrode. (C-D) In vivo stimulation intensity thresholds for evoking EAS EMG reflex responses with 2 mm monopolar ring and 2 mm bipolar ring electrode configurations. (C) Relative stimulation thresholds were dependent on stimulation location (p < 0.001, multi-way ANOVA) but not electrode configuration (p = 0.26). Stimulation at 2 and 3 cm required significantly higher thresholds to evoke an EAS reflex response than stimulation at all other locations (*p < 0.05, Bonferroni post-hoc comparison). (D) Averaged ratio of EAS threshold for bipolar and monopolar 2 mm ring electrodes at different stimulation locations. The ratio of EAS reflex thresholds (bipolar/monopolar) was significantly greater than 1 at 2, 3, and 4 cm from the urethral meatus (*p < 0.05, paired one-sided t-tests).