NEUROPHYSIOLOGYBrainstem microstimulation activates sympathetic fibers in pudendal nerve motor branchJohnson, Richard D.1,2; Hubscher, Charles H.1Author Information 1Department of Physiological Sciences, College of Veterinary Medicine and the University of Florida Brain Institute, University of Florida, Box 100144, Gainesville, FL 32610-0144, USA 2Corresponding Author: Richard D. Johnson Received 6 October 1999; accepted 26 November 1999 Acknowledgements: This research was supported by the American Paralysis Association, NS35702 from the NIH, and the Brain and Spinal Cord Injury Rehabilitation Trust Fund of Florida. The authors thank V. Dugan and R. Odama for excellent technical assistance. NeuroReport: February 7, 2000 - Volume 11 - Issue 2 - p 379-382 Buy Abstract A bilateral spino-bulbo-spinal circuit conveys information from/to the male urogenital tract and perineal muscles. This is the first electrophysiological report of another descending pathway, one which conveys output from the medullary reticular formation (MRF) to activate postganglionic sympathetic fibers contained within the motor branch of the pudendal nerve (PudM). In anesthetized rats, long latency (> 150 ms) discharges were elicited in the PudM following ipsilateral or contralateral microstimulation of the MRF. These firing bursts were not observed in rats after sectioning the lower lumbar sympathetic trunk. The most robust activation was observed when neurons in or near the lateral paragigantocellular reticular nucleus were microstimulated bilaterally. Urogenital dysfunction that occurs following severe spinal cord injury probably results from disrupting these and other supraspinal circuits. © 2000 Lippincott Williams & Wilkins, Inc.