How does the mammalian retina detect motion? This classic problem in visual neuroscience has remained unsolved for 50 years. In search of clues, here we reconstruct Off-type starburst amacrine cells (SACs) and bipolar cells (BCs) in serial electron microscopic images with help from EyeWire, an online community of ‘citizen neuroscientists’. On the basis of quantitative analyses of contact area and branch depth in the retina, we find evidence that one BC type prefers to wire with a SAC dendrite near the SAC soma, whereas another BC type prefers to wire far from the soma. The near type is known to lag the far type in time of visual response. A mathematical model shows how such ‘space–time wiring specificity’ could endow SAC dendrites with receptive fields that are oriented in space–time and therefore respond selectively to stimuli that move in the outward direction from the soma.

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This research was made possible by funding from the Gatsby Charitable Foundation, the Howard Hughes Medical Institute, the Human Frontier Science Program, an anonymous donor, and the National Institutes of Health. K.L. was supported by a Samsung Scholarship. Support from the AWS Research Grants Program gave EyeWire global reach through Amazon Cloudfront. We thank K. Briggman for providing the e2198 data set. J. Mutch created the CNS framework on which CNPKG is based. D. Jia, R. Shearer, and B. Warne assisted in early stages of software development, and W. Silversmith with recent modifications. R. Prentki, L. Trawinski, M. Sorek, A. Ostojic, C. David, R. Avery, S. Temple, A. Bost, M. Greenstein and M. Evans worked in the laboratory to reconstruct neurons, and the first six also served as GrimReaper and hosted EyeWire competitions. Additional reconstructions were provided by R. Han, M. Gavrin, G. Lu, A. Ortiz and D. Udvary. All were trained by R. Prentki, who also created training videos for EyeWirers. We are grateful to A. Norton for 3D renderings, and to E. Almeida for EyeWire graphics. We acknowledge discussions with T. Baden, M. Berry, B. Borghuis, A. Borst, E. J. Chichilnisky, D. Chklovskii, D. Clark, J. Demb, T. Euler, M. Helmstaedter, A. Huberman, S. Lee, R. Masland, J. Sanes and Z. Zhou.

Author information

Author notes

    • Jinseop S. Kim
    •  & Matthew J. Greene

    These authors contributed equally to this work.

    • Mark Richardson
    • , Srinivas C. Turaga
    •  & H. Sebastian Seung

    Present addresses: 601 N 42nd Street, Seattle, Washington 98103, USA (M.R.); Princeton Neuroscience Institute and Computer Science Deptartment, Princeton, New Jersey 08544, USA (H.S.S.); Gatsby Computational Neuroscience Unit, London WC1N 3AR, UK (S.C.T.).


  1. Brain & Cognitive Sciences Department, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

    • Jinseop S. Kim
    • , Matthew J. Greene
    • , Kisuk Lee
    • , Mark Richardson
    • , Srinivas C. Turaga
    • , Michael Purcaro
    • , Matthew Balkam
    • , Amy Robinson
    •  & H. Sebastian Seung
  2. Electrical Engineering and Computer Science Department, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

    • Aleksandar Zlateski
  3. Qualcomm Research, 5775 Morehouse Drive, San Diego, California 92121, USA

    • Bardia F. Behabadi
    •  & Michael Campos
  4. Max-Planck Institute for Medical Research, D-69120 Heidelberg, Germany

    • Winfried Denk


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J.S.K. created algorithms, software and procedures for crowd intelligence and learning, and applied them to generate neuron reconstructions. J.S.K. and M.J.G. classified bipolar cells. M.J.G. analysed contact and co-stratification, aided by code from A.Z. and input from W.D. H.S.S. devised the model with help from B.F.B. and M.C. S.C.T. trained the convolutional network. M.P. and M.B. implemented software and algorithms created by A.Z. for interactive segmentation and 3D visualization, with guidance from S.C.T. M.R. created the EyeWire game and M.B. its data infrastructure. K.L. quantified EyeWirer accuracy and learning. A.R. mobilized and studied the EyeWire community. EyeWirers reconstructed neurons and built extensions to EyeWire. H.S.S. wrote the paper with help from J.S.K., M.J.G. and A.R.

Competing interests

W.D. receives license income for SBEM technology from Gatan Inc.

Corresponding author

Correspondence to H. Sebastian Seung.

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  1. 1.

    Supplementary Information

    This file contains Supplementary Equations showing detailed derivation of the mathematical model of direction selectivity, calculation of the direction selectivity index for a special case that does not depend on the detailed forms of the filters, comparison with experiments, and cable theory estimate of dendritic conduction time. It also contains Supplementary Notes, which include EyeWire demographics, community structure, competitions, and list of EyeWirers who reconstructed SACs.


  1. 1.

    Off SAC with BC2 and BC3a axons.

    Off SAC with BC2 and BC3a axons. Off SAC in red, BC2 axon in yellow, and BC3a axon in blue.

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