Human spinal cord activation during filling and emptying of the bladder
Recording neural activity from the spinal cord is crucial for gaining insights into how it functions. However, the neural activity of the human spinal cord is notoriously difficult to measure. The bony and fascial enclosures combined with the relatively small anatomic size of the spinal cord make it an unfavorable target for traditional functional neuroimaging techniques. Functional ultrasound imaging (fUSI) is an emerging neuroimaging technology that represents a new platform for studying large-scale neural dynamics with high sensitivity, spatial coverage and spatiotemporal resolution. Although it was originally developed for studying brain function, fUSI was recently extended for imaging the spinal cord in animals and humans. While these studies are significant, their primary focus is on the neuroactivation of the spinal cord in response to external sensory stimulations. Here, we combined fUSI with urodynamically-controlled bladder filling and emptying to characterize the hemodynamic response of the human spinal cord during the micturition cycle. Our findings provide the first practical evidence of the existence of bladder pressure-responsive regions, whose hemodynamic signal is strongly correlated with the bladder pressure.