Effects of intracortical microstimulation and vestibular stimulation on pelvic floor muscles in the cat.

Experimental anatomical data in primates and transcranial stimulation of the motor cortex in humans indicate that this region projects to pelvic floor musculature. We investigated this problem in intact, anesthetized cats with intracortical microstimulation (ICMS). Further, we explored the characteristics of projection to pelvic floor muscles from the lateral vestibular nucleus of the brainstem. ICMS reliably produced responses from both recorded muscles, levator ani (LA) and external ani sphincter (EAS). Responses could be obtained both from ipsi and contralateral sides, being shorter for the contralateral ones. In contrast, vestibular stimulation activates only the EAS. It is proposed that these high level inputs to pelvic floor musculature are important for appropriate coordination of defecation and micturition.