Distributed rhythm generators underlie Caenorhabditis elegans forward locomotion

• DOI: 10.7554/elife.29913
• Publication Date: 2018-01-16T00:00:11Z
• Authors: Anthony D Fouad; Shelly Teng; Julian R Mark; Alice Liu; Pilar Alvarez-Illera; Hongfei Ji; Angelica Du; Priya D Bhirgoo; Eli Cornblath; Sihui Asuka Guan; Christopher Fang-Yen
• Keywords: Ablation Techniques; 0301 basic medicine; Periodicity; QH301-705.5; Science; motor circuit; 03 medical and health sciences; Biological Clocks; Animals; Biology (General); optogenetics; Caenorhabditis elegans; Motor Neurons; 0303 health sciences; behavior; Q; rhythm generator; R; Cholinergic Neurons; 3. Good health; locomotion; Optogenetics; CPG; Medicine; Locomotion; Neuroscience

Coordinated rhythmic movements are ubiquitous in animal behavior. In many organisms, chains of neural oscillators underlie the generation of these rhythms. In C. elegans, locomotor wave generation has been poorly understood; in particular, it is unclear where in the circuit rhythms are generated, and whether there exists more than one such generator. We used optogenetic and ablation experiments to probe the nature of rhythm generation in the locomotor circuit. We found that multiple sections of forward locomotor circuitry are capable of independently generating rhythms. By perturbing different components of the motor circuit, we localize the source of secondary rhythms to cholinergic motor neurons in the midbody. Using rhythmic optogenetic perturbation, we demonstrate bidirectional entrainment of oscillations between different body regions. These results show that, as in many other vertebrates and invertebrates, the C. elegans motor circuit contains multiple oscillators that coordinate activity to generate behavior.