Lognormal firing rate distribution reveals prominent fluctuation-driven regime in spinal motor networks

  1. Peter C Petersen
  2. Rune W Berg  Is a corresponding author
  1. University of Copenhagen, Denmark


When spinal circuits generate rhythmic movements it is important that the neuronal activity remains within stable bounds to avoid saturation and to preserve responsiveness. Here, we simultaneously record from hundreds of neurons in lumbar spinal circuits of turtles and establish the neuronal fraction that operates within either a 'mean-driven' or a 'fluctuation-driven' regime. Fluctuation-driven neurons have a 'supralinear' input-output curve, which enhances sensitivity, whereas the mean-driven regime reduces sensitivity. We find a rich diversity of firing rates across the neuronal population as reflected in a lognormal distribution and demonstrate that half of the neurons spend at least 50% of the time in the 'fluctuation-driven' regime regardless of behavior. Because of the disparity in input-output properties for these two regimes, this fraction may reflect a fine trade-off between stability and sensitivity in order to maintain flexibility across behaviors.

Article and author information

Author details

  1. Peter C Petersen

    Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
    Competing interests
    The authors declare that no competing interests exist.
  2. Rune W Berg

    Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-6376-9368


Sundhed og Sygdom, Det Frie Forskningsråd

  • Rune W Berg

Novo Nordisk

  • Rune W Berg

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.


Animal experimentation: The surgical procedures comply with Danish legislation and were approved by the controlling body under the Ministry of Justice.

Reviewing Editor

  1. Jan-Marino Ramirez, Seattle Children's Research Institute and University of Washington, United States

Publication history

  1. Received: June 14, 2016
  2. Accepted: October 25, 2016
  3. Accepted Manuscript published: October 26, 2016 (version 1)
  4. Version of Record published: December 2, 2016 (version 2)
  5. Version of Record updated: August 14, 2017 (version 3)


© 2016, Petersen & Berg

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.


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  1. Peter C Petersen
  2. Rune W Berg
Lognormal firing rate distribution reveals prominent fluctuation-driven regime in spinal motor networks
eLife 5:e18805.

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