The sequential activation of neurons has been observed in various areas of the brain, but in no case is the underlying network structure well understood. Here we examined the circuit anatomy of zebra finch HVC, a cortical region that generates sequences underlying the temporal progression of the song. We combined serial block-face electron microscopy with light microscopy to determine the cell types targeted by HVC(RA) neurons, which control song timing. Close to their soma, axons almost exclusively targeted inhibitory interneurons, consistent with what had been found with electrical recordings from pairs of cells. Conversely, far from the soma the targets were mostly other excitatory neurons, about half of these being other HVC(RA) cells. Both observations are consistent with the notion that the neural sequences that pace the song are generated by global synaptic chains in HVC embedded within local inhibitory networks.
Original language | English |
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Article number | e24364 |
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Journal | eLife |
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Volume | 6 |
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DOIs | |
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Publication status | Published - 27 Mar 2017 |
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Externally published | Yes |
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This research was supported by the National Institutes of Health (Grant R01NS075044) (M.A.L.) and (F31 NS084767) (S.E.B.), the New York Stem Cell Foundation (M.A.L.), the Max Planck Society (J.K., F.S. R.T.N., M.O., W.D), the Bernstein Center for Computational Neuroscience, Boehringer Ingelheim Foundation (J.K., F.S.), the German Federal Ministry of Education and Research Grant BMBF/FKZ 01GQ1002 (M.O.), and the European Research Council (M.O.) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 633428). We thank L. Gibb, M. Halassa, D. Jin, K. Katlowitz, G. Kosche, M. Picardo A. Reyes, D. Rinberg, R. Tremblay, and D. Vallentin for comments on the manuscript. We are grateful to A. Al-Shaboti, A. Andrade Garcia, E. Atsiatorme, D. Baltissen, S. Bassler, F. Bassler, J. Bessler, D. Dimitrov, M. Ederer, T. Eliguezel, O. Fedorashko, L. Fey, J. Foehr, A. Gaubatz, S. Gottwalt, M. Gross, J. Hammerich, L. Hammes, H. Hees, J. Hendricks, J. Huether, S. Hutzl, R. Janssen, K. Kappler, F. Kaufhold, K. Kehrle, K. Kiesl, J. Kupke, J. Loeffler, S. Mertens, O. Mueller, T. Noel, L. Obenauer, G. Patzer, J. Pellegrino, D. Raica, C. Sandhof, M. Schramm, J. Schwab, D. Schwarz, J. Serwani, A. Sons, J. Tytko, D. Wachmann, and S. Zaschke for help with EM data analysis, J. Kuhl for help with figure preparation, and J. Tritthardt for building custom electronics.