Figure 6

A simple working model of the lower urinary tract control system, showing the voiding reflex and brainstem (green) and forebrain circuits 1, 2 and 3 (red/blue, yellow and blue, respectively). Circuit 1 includes the thalamus (th) and insula, which is regarded as the homeostatic afferent cortex. The insula processes visceral sensations and sends information about the state of the bladder to the medial prefrontal cortex (mPFC), which is thought to provide modulatory feedback to PAG-PMC circuits. Lesions in the mPFC can induce incontinence. Circuit 2 includes the dorsal anterior cingulate cortex (dACC) and the supplementary motor area (SMA), which are thought to be involved in motivation and modulation of body arousal states. These areas are activated when patients experience a sense of urinary urgency and are thought to trigger responses of the urethral outlet to postpone voiding. Circuit 3 is thought to be concerned with the emotional aspects of voiding. IPFC, lateral prefrontal cortex. Reprinted with permission from (1): de Groat WC, Griffiths D, Yoshimura N. (2015) Neural control of the lower urinary tract. Compr. Physiol. 5:327–96. doi: 10.1002/cphy.c130056.