1. Neuroscience
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Slowly evolving dopaminergic activity modulates the moment-to-moment probability of reward-related self-timed movements

  1. Allison E Hamilos  Is a corresponding author
  2. Giulia Spedicato
  3. Ye Hong
  4. Fangmiao Sun
  5. Yulong Li
  6. John Assad
  1. Harvard Medical School, United States
  2. Peking University School of Life Science, China
  3. Peiking University School of Life Sciences, China
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Cite this article as: eLife 2021;10:e62583 doi: 10.7554/eLife.62583

Abstract

Clues from human movement disorders have long suggested that the neurotransmitter dopamine plays a role in motor control, but how the endogenous dopaminergic system influences movement is unknown. Here we examined the relationship between dopaminergic signaling and the timing of reward-related movements in mice. Animals were trained to initiate licking after a self-timed interval following a start-timing cue; reward was delivered in response to movements initiated after a criterion time. The movement time was variable from trial-to-trial, as expected from previous studies. Surprisingly, dopaminergic signals ramped-up over seconds between the start-timing cue and the self-timed movement, with variable dynamics that predicted the movement/reward time on single trials. Steeply rising signals preceded early lick-initiation, whereas slowly rising signals preceded later initiation. Higher baseline signals also predicted earlier self-timed movements. Optogenetic activation of dopamine neurons during self-timing did not trigger immediate movements, but rather caused systematic early-shifting of movement initiation, whereas inhibition caused late-shifting, as if modulating the probability of movement. Consistent with this view, the dynamics of the endogenous dopaminergic signals quantitatively predicted the moment-by-moment probability of movement initiation on single trials. We propose that ramping dopaminergic signals, likely encoding dynamic reward expectation, can modulate the decision of when to move.

Data availability

All datasets supporting the findings of this study are publicly available (DOI: 10.5281/zenodo.4062749). Source data files have been provided for all figures.

The following data sets were generated

Article and author information

Author details

  1. Allison E Hamilos

    Department of Neurobiology, Harvard Medical School, Boston, United States
    For correspondence
    allisonhamilos@gmail.com
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9486-0017
  2. Giulia Spedicato

    Department of Neurobiology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.
  3. Ye Hong

    Department of Neurobiology, Harvard Medical School, Boston, United States
    Competing interests
    No competing interests declared.
  4. Fangmiao Sun

    State Key Laboratory of Membrane Biology, Peking University School of Life Science, Beijing, China
    Competing interests
    No competing interests declared.
  5. Yulong Li

    State Key Laboratory of Membrane Biology, Peiking University School of Life Sciences, Beijing, China
    Competing interests
    No competing interests declared.
  6. John Assad

    Department of Neurobiology, Harvard Medical School, Boston, United States
    Competing interests
    John Assad, co-founder of OptogeniX, which produces the tapered optical fibers used in some experiments..

Funding

National Institutes of Health (UF-NS108177)

  • John Assad

National Institutes of Health (U19 NS113201)

  • John Assad

National Institutes of Health (EY-12196)

  • John Assad

Lefler Predoctoral Fellowship (n/a)

  • Allison E Hamilos

Stuart H.Q. and Victoria Quan Predoctoral Fellowship (n/a)

  • Allison E Hamilos

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

Ethics

Animal experimentation: All experiments and protocols were approved by the Harvard Institutional Animal Care and Use Committee (IACUC protocol #05098, Animal Welfare Assurance Number #A3431-01) and were conducted in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Surgeries were conducted under aseptic conditions with isoflurane anesthesia, and every effort was taken to minimize suffering.

Reviewing Editor

  1. Jesse H Goldberg, Cornell University, United States

Publication history

  1. Received: August 29, 2020
  2. Accepted: December 21, 2021
  3. Accepted Manuscript published: December 23, 2021 (version 1)

Copyright

© 2021, Hamilos et al.

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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