title: Hierarchical sparse coding in the sensory system of Caenorhabditis elegans.
abstract: Animals with compact sensory systems face an encoding problem where a small number of sensory neurons are required to encode information about its surrounding complex environment. Using Caenorhabditis elegans worms as a model, we ask how chemical stimuli are encoded by a small and highly connected sensory system. We first generated a comprehensive library of transgenic worms where each animal expresses a genetically encoded calcium indicator in individual sensory neurons. This library includes the vast majority of the sensory system in C. elegans. Imaging from individual sensory neurons while subjecting the worms to various stimuli allowed us to compile a comprehensive functional map of the sensory system at single neuron resolution. The functional map reveals that despite the dense wiring, chemosensory neurons represent the environment using sparse codes. Moreover, although anatomically closely connected, chemo- and mechano-sensory neurons are functionally segregated. In addition, the code is hierarchical, where few neurons participate in encoding multiple cues, whereas other sensory neurons are stimulus specific. This encoding strategy may have evolved to mitigate the constraints of a compact sensory system.
authors.affiliation: Genetics Department, Silberman Life Science Institute, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; and pws@caltech.edu alonzas@mail.huji.ac.il.
authors.forename: Alon
authors.initials: A
authors.lastname: Zaslaver
authors.affiliation: Genetics Department, Silberman Life Science Institute, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; and.
authors.forename: Idan
authors.initials: I
authors.lastname: Liani
authors.affiliation: Genetics Department, Silberman Life Science Institute, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; and.
authors.forename: Oshrat
authors.initials: O
authors.lastname: Shtangel
authors.affiliation: Genetics Department, Silberman Life Science Institute, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; and.
authors.forename: Shira
authors.initials: S
authors.lastname: Ginzburg
authors.affiliation: Howard Hughes Medical Institute and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Lisa
authors.initials: L
authors.lastname: Yee
authors.affiliation: Howard Hughes Medical Institute and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125 pws@caltech.edu alonzas@mail.huji.ac.il.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sternberg
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified / Q000502:physiology; D017173:Caenorhabditis elegans / Q000166:cytology / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D009415:Nerve Net / Q000166:cytology / Q000502:physiology*; D011984:Sensory Receptor Cells / Q000166:cytology / Q000502:physiology*
chemical_list: D002118:Calcium
keywords: calcium imagaing; neural circuits; sensory coding