The central nervous system control of micturition in cats and humans

Recent findings concerning the central control of micturition in cats are compared to findings obtained from dynamic imaging studies in humans. In the cat, three areas in the brainstem and diencephalon are specifically implicated in the control of micturition: (1) Barrington's nucleus or the pontine micturition center in the dorsomedial pontine tegmentum directly excites bladder motoneurons and indirectly inhibits, via inhibitory interneurons in the medial sacral cord, urethral sphincter motoneurons; (2) the periaqueductal grey receiving bladder filling information; and (3) the pre-optic area of the hypothalamus possibly involved in determining the beginning of micturition. According to PET-scan studies, in humans the same supraspinal regions are active during micturition. In the cat another area, located in the ventrolateral pontine tegmentum and is called the L-region, which controls the motoneurons of the pelvic floor, including the external urethral sphincter. This region might be considered as the pontine storage center. In humans the L-region is especially active in volunteers who tried but did not succeed to micturate. The results suggest that in cats and humans at the brainstem and diencephalic levels micturition is organized in the same way.