Understanding functional connectivity of sensory and motor pathways to specific regions of the lower urinary tract.

This foundational project will produce mesoscopic and microscopic functional anatomical maps of the sensory and autonomic (motor) neurons that regulate the lower urinary tract (LUT). Neural dysfunction is a major contributor to diverse, largely intractable urological problems, including overactive or underactive bladder, incontinence due to ageing or pelvic surgery, and painful bladder syndrome/interstitial cystitis. We will fill knowledge gaps and overcome diverse technical roadblocks to develop maps that provide a critical foundation for modeling different LUT behaviors, understanding neuromodulatory mechanisms, and determining off-target effects of neuromodulation. We will conduct this study in adult rats, the species where the peripheral and spinal circuitry of the LUT is defined in the most detail and, compared with mice, their larger size facilitates development of devices. Together, this will facilitate development of new methods for normalizing over- or underactivity in these circuits. The aims to be addressed in males and females are: (1) To map functionally distinct classes of sensory and autonomic neurons that innervate the bladder body, trigone and proximal urethra. We will also map neurons that project to more than one of these regions (`cross-talk'). In addition to known functional markers of sensory and autonomic neural subtypes, we will use the latest outcomes of our RNA-seq analyses of retrogradely labeled bladder-projecting neurons to define and map new markers of functional subclasses. (2) To map the spinal targets of sensory neurons innervating the bladder body, trigone and proximal urethra. Using viral tracing we will map and characterize second order sensory neurons in autonomic reflex and nociceptive pathways; we will also identify sites of convergence from two peripheral targets. (3) To map the spinal neurons activated by physiologically- or electrically-induced voiding in conscious rats. Our recent advance of activating pelvic nerves in chronically- catheterized conscious animals will be combined with markers of neural activation, detailed phenotyping of activated neurons and viral tracing.