title: Neural and genetic degeneracy underlies Caenorhabditis elegans feeding behavior.
abstract: Degenerate networks, in which structurally distinct elements can perform the same function or yield the same output, are ubiquitous in biology. Degeneracy contributes to the robustness and adaptability of networks in varied environmental and evolutionary contexts. However, how degenerate neural networks regulate behavior in vivo is poorly understood, especially at the genetic level. Here, we identify degenerate neural and genetic mechanisms that underlie excitation of the pharynx (feeding organ) in the nematode Caenorhabditis elegans using cell-specific optogenetic excitation and inhibition. We show that the pharyngeal neurons MC, M2, M4, and I1 form multiple direct and indirect excitatory pathways in a robust network for control of pharyngeal pumping. I1 excites pumping via MC and M2 in a state-dependent manner. We identify nicotinic and muscarinic receptors through which the pharyngeal network regulates feeding rate. These results identify two different mechanisms by which degeneracy is manifest in a neural circuit in vivo.
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and.
authors.forename: Nicholas F
authors.initials: NF
authors.lastname: Trojanowski
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania;
authors.forename: Olivia
authors.initials: O
authors.lastname: Padovan-Merhar
authors.affiliation: Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania; raizen@mail.med.upenn.edu.
authors.forename: David M
authors.initials: DM
authors.lastname: Raizen
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania; and Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul, South Korea.
authors.forename: Christopher
authors.initials: C
authors.lastname: Fang-Yen
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005247:Feeding Behavior; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000502:physiology; D009415:Nerve Net / Q000166:cytology* / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D062308:Optogenetics; D010614:Pharynx / Q000294:innervation / Q000502:physiology; D011976:Receptors, Muscarinic / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000378:metabolism
chemical_list: D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic
keywords: behavior; feeding; neural circuits; optogenetics