1. Neuroscience
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Conserved visual capacity of rats under red light

  1. Nader Nikbakht  Is a corresponding author
  2. Mathew E Diamond  Is a corresponding author
  1. MIT, United States
  2. International School for Advanced Studies, Italy
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Cite this article as: eLife 2021;10:e66429 doi: 10.7554/eLife.66429


Recent studies examine the behavioral capacities of rats and mice with and without visual input, and the neuronal mechanisms underlying such capacities. These animals are assumed to be functionally blind under red light, an assumption that might originate in the fact that they are dichromats who possess ultraviolet and green but not red cones. But the inability to see red as a color does not necessarily rule out form vision based on red light absorption. We measured Long-Evans rats' capacity for visual form discrimination under red light of various wavelength bands. Upon viewing a black and white grating, they had to distinguish between two categories of orientation, horizontal and vertical. Psychometric curves plotting judged orientation versus angle demonstrate the conserved visual capacity of rats under red light. Investigations aiming to explore rodent physiological and behavioral functions in the absence of visual input should not assume red-light blindness.

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All data generated or analyzed during this study will be included in the manuscript and supporting files. Source code files will be provided for Figures 1 and 2 at https://github.com/nadernik/nikbakht_diamond_elife

Article and author information

Author details

  1. Nader Nikbakht

    Brain and Cognitive Sciences, MIT, Cambridge, United States
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-9726-9115
  2. Mathew E Diamond

    Cognitive Neuroscience, International School for Advanced Studies, Trieste, Italy
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2286-4566


European Research Council (294498)

  • Mathew E Diamond

Human Frontier Science Program (RGP0015/2013)

  • Mathew E Diamond

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


Animal experimentation: The rats were under the care of a consulting veterinarian. Study protocols conformed to international norms and were approved by the Ethics Committee of SISSA and by the Italian Health Ministry (license numbers 569/2015-PR and 570/2015-PR).

Reviewing Editor

  1. Martin Vinck, Ernst Strüngmann Institute (ESI) for Neuroscience in Cooperation with Max Planck Society, Germany

Publication history

  1. Received: January 11, 2021
  2. Accepted: July 19, 2021
  3. Accepted Manuscript published: July 20, 2021 (version 1)


© 2021, Nikbakht & Diamond

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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