Professor, Department of Genetics
Siegfried Ullmann Chair in Molecular Genetics
How complex neural circuits form and how they function are major unsolved problems in neurobiology. We use the nematode Caenorhabditis elegans to study these questions at the cellular and genetic levels. We have recently described the complete synaptic connectivity in the neural network that governs the mating behavior of the C. elegans male (Jarrell et al., 2012, Science 337, 437-444. PDF available at http://wormwiring.org). Reconstruction of the remaining circuitry in the male nervous system, nearly completed, will yield the male connectome. We identify synapses and the trajectories of neurons by analysis of serial section electron micrographs, making use of a novel software platform. Our male wiring diagram, together with that of the adult hermaphrodite, first published in 1986 and currently undergoing updating in our laboratory, completes the description of nervous system connectivity for the adults of C. elegans, the only animal species for which this information is available.
Einstein has recently acquired state-of-the art capability for generating vastly improved electron microscopic datasets of serially sectioned neural tissue. With this facility, new connectomics data from far larger volumes may be obtained with unprecedented speed. We plan to reconstruct additional connectomes of C. elegans, from embryonic and larval stages or from mutants, for example. Projects focused on material from mammalian or other vertebrate brain tissue are contemplated.
The neural network for C. elegans male copulation consists of the processes of some 144 neurons and 8,000 synapses. We analyze the patterns of connectivity within this network using computational methods to identify pathways that subserve particular steps of behavior. Hypotheses regarding neuron function are experimentally tested by cell killing techniques. We probe the functions of classical and peptide neurotransmitters, their receptors, and gap junctions by genetic methods.
To determine how a neural network is genetically specified, we make use of transgenes that express fluorescent proteins targeted to specific synapses. We plan to use these synapse-specific labels to identify mutants and genes that affect formation of particular cellular synaptic contacts. In these experiments we hope to uncover the still elusive class of proteins that encode the molecular determinants of synaptic specificity.
Lints, R., Jia, L., Kim, K., Li, C., and Emmons, S.W. (2004) Axial patterning of C. elegans male sensilla identities by selector genes. Dev. Biol. 269, 137-151.
Portman, D.S. and Emmons, S.W. (2004) Identification of C. elegans sensory ray genes using whole-genome expression profiling. Dev. Biol. 270, 499-512.
Lipton, J., Kleemann, G., Ghosh, R., Lints, R., and Emmons, S.W. (2004) Mate-searching in Caenorhabditis elegans: A genetic model for sex drive in a simple invertebrate. J. Neurosci. 24, 7427-7434.
Emmons, S.W. (2005) Male development (November 10, 2005), WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.33.1, http://www.wormbook.org.
Jia, L., and Emmons, S. W. (2006). Genes that control ray sensory neuron axon development in the Caenorhabditis elegans male. Genetics 173, 1241-1258.
Ghosh, R., and Emmons, S. W. (2008) Episodic swimming behavior in the nematode C. elegans. Journal of Experimental Biology 211, 3703-3711.
Barrios, A., Nurrish, S., and Emmons, S. W. (2008) Sensory regulation of C. elegans male mate-searching behavior. Current Biology 18, 1865-1871.
Kleemann, G., Jia, L., and Emmons, S.W. (2008). Regulation of Caenorhabditis elegans male mate searching behavior by the nuclear receptor DAF-12. Genetics 180, 2111-2122.
Zhang, H., and Emmons, S.W. (2009). Regulation of the C. elegans posterior Hox gene egl-5 by microRNA and the Polycomb-like gene sop-2. Developmental Dynamics 238, 595-603.
Ghosh, R., and Emmons, S. W. (2010) Calcineurin and protein kinase G regulate C. elegans behavioral quiescence during locomotion in liquid. BMC Genetics 11:7.
Jarrell. T. A., Wang, Y., Bloniarz, A. E., Brittin, C. A., Xu, M., Thomson, J. N., Albertson, D. G., Hall, D. H., and Emmons, S. W. (2012) The connectome of a decision-making neural network. Science 337, 437-444.
Emmons, S. W. (2012) The mood of a worm (Perspective). Science 338, 475-476.
Barrios, A., Ghosh, R., Fang, C., Emmons, S.W., and Barr, M.M. PDF-1 neuropeptide signaling modulates a neural circuit for mate-searching behavior in C. elegans, Nature Neuroscience, in press.
Xu, M., Jarrell, T. A., Wang, Y., Cook, S. J., Hall, D. H., and Emmons, S. W. Computer assisted assembly of connectomes from electron micrographs: Application to C. elegans. PlosONE, accepted pending minor revision.
More Information About Dr. Scott Emmons
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Albert Einstein College of Medicine
Jack and Pearl Resnick Campus
1300 Morris Park Avenue
Ullmann Building, Room 703
Bronx, NY 10461
Nature.com interviews Dr. Scott Emmons about his study that determined the complete neural diagram that governs male roundworm mating behavior.
Scientific American’s "Scicurious" blog features research by Dr. Scott Emmons that maps the neural pathways controlling male roundworm mating.