The medial prefrontal cortex (mPFC) is located behind the forehead at the front of the cortex (green), while the pontine micturition center (PMC) and the locus coeruleus (LC) are located within a part of the brainstem known as the pons (blue). The approximate locations of these regions within the human brain are shaded in the cartoon on the left. These three brain regions both send and receive signals (represented by arrows) to and from each other. Signals from the bladder are relayed via the spinal cord to the LC, and then to other centers in the brain including the PMC. The PMC sends signals to the bladder via the spinal cord. The PMC contains different kinds of neurons. Neurons expressing corticotropin-releasing hormone are labeled Crh+, and are known to be involved in starting urination. Neurons that do not express this hormone are labelled Crh-. The role of these neurons is less clear, but it is possible that they are involved in urine storage. Glut+ and GABA+ indicate neurons that produce glutamate and GABA, respectively. Confirmed connections with unclear effects are marked with a red question mark.