TY - JOUR T1 - A descending pathway through electrical coupling facilitates undulatory wave propagation in <em>C. elegans</em> JF - bioRxiv DO - 10.1101/131490 SP - 131490 AU - Tianqi Xu AU - Jing Huo AU - Shuai Shao AU - Michelle Po AU - Taizo Kawano AU - Yangning Lu AU - Min Wu AU - Mei Zhen AU - Quan Wen Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/06/18/131490.abstract N2 - Descending signals from the brain play critical roles in controlling and modulating locomotion kinematics. The anatomical wiring diagram of the C. elegans nervous system suggests that the premotor interneurons AVB, the hub for sensorimotor transformation, make exclusively electrical synapses with the B-type motor neurons that activate body wall muscles and drive forward locomotion. Here, we combined genetic analysis, optogenetic manipulation, and computational modeling to elucidate the functions of AVB-B electrical couplings. First, we found that B-type motor neurons could intrinsically generate rhythmic activity, constituting distributed center pattern generators. Second, AVB-B electrical couplings provide a descending pathway to drive bifurcation of motor neuron dynamics, triggering their transition from being stationary to generating rhythmic activity. Third, directional proprioceptive couplings between neighboring B-type motor neurons entrain the undulation frequency, forcing coherent bending waves to propagate from head to tail. Together, we propose that AVB-B electrical couplings work synergistically with proprioceptive couplings to enhance sequential activation of motor activity, and to facilitate the propagation of body undulation from head to tail during C. elegans forward locomotion. ER -