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. 2014 May 20;8:42. doi: 10.3389/fnint.2014.00042

FIGURE 1.

FIGURE 1

Facilitation of the pudendal anal reflex (PAR) by single pulse transcranial agnetic stimulation (TMS) of the motor cortex. (A) Experimental set-up showing position of dorsal penile nerve stimulating electrodes (DPN), anal sphincter EMG recording electrode and the TMS double cone coil. Insets: idealized PAR and anal sphincter motor evoked potential (MEP) responses. (B-E) Anal sphincter EMG averaged (n = 10) evoked responses in a control subject. (B) MEP to cortical TMS at 50% maximum stimulator output (MSO). (C) PAR response to stimulation of the DPN at 2.6 times sensory threshold (18 mA). (D) Lack of response to TMS at 45% MSO. (E) TMS at 45% MSO preceding DPN at 2.6 times sensory threshold by 30 ms. The DPN stimulus in E now elicits an enhanced PAR that is approximately double the peak-to-peak size of the unconditioned PAR in (C). (F) The degree of facilitation of the PAR by TMS at different conditioning intervals. Negative intervals indicate that the TMS occurred prior to the DPN stimuli. The graph presents the average (mean ± SE) percentage increase in the PAR for three control (open symbols) and three iSCI (closed symbols) subjects. The dashed horizontal line represents a level of zero facilitation. The degree of facilitation is significantly greater for the control group (Wilcoxon signed rank test P = 0.008).