SCOTT W. EMMONS, Ph.D.

Development and Function of Neural Circuits, Connectomics 

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.

            Visit our websites: http://worms.aecom.yu.edu  http://wormwiring.org