The brain’s ability to prioritize voluntary behaviors is essential for species propagation and self-survival. Of these, initiating and sustaining exploratory behavior for seeking mates or resources requires goal-directed locomotion. However, this intentional choice to move suppresses other voluntary behaviors, including urination and defecation, as controlling when and where to excrete is critical when time is limited (as highlighted in the image above).
In this preprint (https://www.biorxiv.org/cgi/content/short/2026.07.23.736864v1), we define a functional hypothalamic-hindbrain circuit in mice that promotes locomotion while eliminating urination and defecation for hours. Chemogenetic stimulation of excitatory estrogen-melanocortin-responsive MC4R+ neurons in the ventrolateral ventromedial hypothalamus (VMHvl) effectively silences bladder and colonic visceral reflexes, even at noxious distension pressures, underscoring the potency of this anti-excretion circuit. Our study illustrates how a hormone-responsive brain node optimizes an essential voluntary behavior for evolutionary fitness.
Photo from the 2026 SF Marathon, courtesy of Archana's mother.