Abstract

Survival in threatening situations depends on the selection and rapid execution of an appropriate active or passive defensive response, yet the underlying brain circuitry is not understood. Here we use circuit-based optogenetic, in vivo and in vitro electrophysiological, and neuroanatomical tracing methods to define midbrain periaqueductal grey circuits for specific defensive behaviours. We identify an inhibitory pathway from the central nucleus of the amygdala to the ventrolateral periaqueductal grey that produces freezing by disinhibition of ventrolateral periaqueductal grey excitatory outputs to pre-motor targets in the magnocellular nucleus of the medulla. In addition, we provide evidence for anatomical and functional interaction of this freezing pathway with long-range and local circuits mediating flight. Our data define the neuronal circuitry underlying the execution of freezing, an evolutionarily conserved defensive behaviour, which is expressed by many species including fish, rodents and primates. In humans, dysregulation of this ‘survival circuit’ has been implicated in anxiety-related disorders.

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Acknowledgements

We thank C. Müller, J. Lüdke, K. Bylund, J. Alonso, T. Lu, P. Argast and P. Buchmann for technical assistance, J. J. Letzkus for input on the manuscript, and all members of the Lüthi and Arber laboratories for discussions and other help with the project. We thank L. Gelman and S. Bourke for help with microscopy, and M. Stadler for statistical advice. We are grateful to G. Keller for providing viruses for optogenetics, Z. J. Huang for initially providing the Gad2-ires-Cre mouse line and L. Xiao and P. Scheiffele for the anti-rabiesG antibody. This work was supported by the Novartis Research Foundation, by the National Center of Competences in Research: ‘SYNAPSY — The Synaptic Bases of Mental Diseases’ (financed by the Swiss National Science Foundation) as well as by a Swiss National Science Foundation Core Grant, and a European Research Council Advanced Grant to A.L. Support for S.A. and M.S.E. was provided by a European Research Council Advanced Grant, the Swiss National Science Foundation and the Kanton Basel-Stadt. P.T. and J.P.F. were supported by NARSAD Young Investigator Grants by the Brain and Behavior Foundation. M.S.E. was also supported by a long-term post-doctoral fellowship of the Human Frontier Science Program and a Synapsis Foundation Grant. F.C. and C.H. were supported by grants from the European Research Council (ERC) under the European Union’s Seventh Framework Program (FP7/2007-2013)/ERC grant agreement number 281168 and the Fondation pour la Recherche Médicale.

Author information

Author notes

    • Paolo Botta
    •  & Steffen B. E. Wolff

    Present addresses: Champalimaud Centre for the Unknown, Avenida de Brasilia, 1400-038 Lisbon, Portugal (P.B.); Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA (S.B.E.W.).

    • Philip Tovote
    •  & Maria Soledad Esposito

    These authors contributed equally to this work.

Affiliations

  1. Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland

    • Philip Tovote
    • , Maria Soledad Esposito
    • , Paolo Botta
    • , Jonathan P. Fadok
    • , Milica Markovic
    • , Steffen B. E. Wolff
    • , Silvia Arber
    •  & Andreas Lüthi
  2. Biozentrum, Department of Cell Biology, University of Basel, 4056 Basel, Switzerland

    • Maria Soledad Esposito
    •  & Silvia Arber
  3. INSERM, Neurocentre Magendie, U862, 146 Rue Léo-Saignat, Bordeaux 33077, France

    • Fabrice Chaudun
    •  & Cyril Herry
  4. Stanford University, 318 Campus Drive West, Clark Center W080, Stanford, California 94305, USA

    • Charu Ramakrishnan
    • , Lief Fenno
    •  & Karl Deisseroth

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Contributions

P.T. conceived, designed, performed and analysed most of the experiments and wrote the manuscript. M.S.E. conceived, designed, performed and analysed neuroanatomical tracing experiments. P.B. performed and analysed in vitro slice recordings. F.C. and C.H. performed single-unit recordings in the PAG. S.B.E.W. established optogenetic methodology. J.P.F. performed experiments. M.M. designed and tested viruses for optogenetics. C.R., L.F. and K.D. produced viruses for optogenetics. S.A. designed viruses for tracing and optogenetics. A.L. conceived the project and wrote the manuscript. All authors contributed to the experimental design and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Philip Tovote or Andreas Lüthi.

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    Supplementary Information

    This file contains a Supplementary Discussion, Statistics Table and Supplementary References.

Videos

  1. 1.

    Freezing behavior evoked by activation of glutamatergic vlPAG neurons.

    Freezing behavior evoked by activation of glutamatergic vlPAG neurons.

  2. 2.

    Inhibition of glutamatergic vlPAG neurons diminishes conditioned cued freezing

    Inhibition of glutamatergic vlPAG neurons diminishes conditioned cued freezing.

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    Selective activation of glutamatergic vlPAG neurons projecting to Mc evokes freezing behavior

    Selective activation of glutamatergic vlPAG neurons projecting to Mc evokes freezing behavior.

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https://doi.org/10.1038/nature17996

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