Botulinum neurotoxin accurately separates tonic vs phasic transmission and reveals heterosynaptic plasticity rules in Drosophila

  1. Yifu Han
  2. Chun Chien
  3. Pragya Goel
  4. Kaikai He
  5. Cristian Pinales
  6. Christopher Buser
  7. Dion K Dickman  Is a corresponding author
  1. University of Southern California, United States
  2. Oak Crest Institute of Science, United States

Abstract

In developing and mature nervous systems, diverse neuronal subtypes innervate common targets to establish, maintain, and modify neural circuit function. A major challenge towards understanding the structural and functional architecture of neural circuits is to separate these inputs and determine their intrinsic and heterosynaptic relationships. The Drosophila larval neuromuscular junction is a powerful model system to study these questions, where two glutamatergic motor neurons, the strong phasic-like <strong>Is</strong> and weak tonic-like <strong>Ib</strong>, co-innervate individual muscle targets to coordinate locomotor behavior. However, complete neurotransmission from each input has never been electrophysiologically separated. We have employed a botulinum neurotoxin, BoNT-C, that eliminates both spontaneous and evoked neurotransmission without perturbing synaptic growth or structure, enabling the first approach that accurately isolates input-specific neurotransmission. Selective expression of BoNT-C in Is or Ib motor neurons disambiguates the functional properties of each input. Importantly, the blended values of Is+Ib neurotransmission can be fully recapitulated by isolated physiology from each input. Finally, selective silencing by BoNT-C does not induce heterosynaptic structural or functional plasticity at the convergent input. Thus, BoNT-C establishes the first approach to accurately separate neurotransmission between tonic vs phasic neurons and defines heterosynaptic plasticity rules in a powerful model glutamatergic circuit.

Data availability

All data generated or analyzed during this study are included in the manuscript and supporting files. In particular, full details of the data are included in Supplemental files 1 and 2.

Article and author information

Author details

  1. Yifu Han

    Department of Neurobiology, University of Southern California, Los Angeles, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-1201-654X
  2. Chun Chien

    Department of Neurobiology, University of Southern California, Los Angeles, United States
    Competing interests
    No competing interests declared.
  3. Pragya Goel

    Department of Neurobiology, University of Southern California, Los Angeles, United States
    Competing interests
    No competing interests declared.
  4. Kaikai He

    Department of Neurobiology, University of Southern California, Los Angeles, United States
    Competing interests
    No competing interests declared.
  5. Cristian Pinales

    Oak Crest Institute of Science, Monrovia, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-0826-5308
  6. Christopher Buser

    Oak Crest Institute of Science, Monrovia, United States
    Competing interests
    No competing interests declared.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-4379-3878
  7. Dion K Dickman

    Department of Neurobiology, University of Southern California, Los Angeles, United States
    For correspondence
    dickman@usc.edu
    Competing interests
    Dion K Dickman, Reviewing editor, eLife.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-1884-284X

Funding

National Institutes of Health (NS091546)

  • Dion K Dickman

National Institutes of Health (NS111414)

  • Dion K Dickman

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

Copyright

© 2022, Han 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.

Metrics

  • 2,610
    views
  • 448
    downloads
  • 18
    citations

Views, downloads and citations are aggregated across all versions of this paper published by eLife.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Yifu Han
  2. Chun Chien
  3. Pragya Goel
  4. Kaikai He
  5. Cristian Pinales
  6. Christopher Buser
  7. Dion K Dickman
(2022)
Botulinum neurotoxin accurately separates tonic vs phasic transmission and reveals heterosynaptic plasticity rules in Drosophila
eLife 11:e77924.
https://doi.org/10.7554/eLife.77924

Share this article

https://doi.org/10.7554/eLife.77924

Further reading

    1. Neuroscience
    Magdalena Solyga, Georg B Keller
    Research Article

    Our movements result in predictable sensory feedback that is often multimodal. Based on deviations between predictions and actual sensory input, primary sensory areas of cortex have been shown to compute sensorimotor prediction errors. How prediction errors in one sensory modality influence the computation of prediction errors in another modality is still unclear. To investigate multimodal prediction errors in mouse auditory cortex, we used a virtual environment to experimentally couple running to both self-generated auditory and visual feedback. Using two-photon microscopy, we first characterized responses of layer 2/3 (L2/3) neurons to sounds, visual stimuli, and running onsets and found responses to all three stimuli. Probing responses evoked by audiomotor (AM) mismatches, we found that they closely resemble visuomotor (VM) mismatch responses in visual cortex (V1). Finally, testing for cross modal influence on AM mismatch responses by coupling both sound amplitude and visual flow speed to the speed of running, we found that AM mismatch responses were amplified when paired with concurrent VM mismatches. Our results demonstrate that multimodal and non-hierarchical interactions shape prediction error responses in cortical L2/3.

    1. Neuroscience
    Gyeong Hee Pyeon, Hyewon Cho ... Yong Sang Jo
    Research Article Updated

    Recent studies suggest that calcitonin gene-related peptide (CGRP) neurons in the parabrachial nucleus (PBN) represent aversive information and signal a general alarm to the forebrain. If CGRP neurons serve as a true general alarm, their activation would modulate both passive nad active defensive behaviors depending on the magnitude and context of the threat. However, most prior research has focused on the role of CGRP neurons in passive freezing responses, with limited exploration of their involvement in active defensive behaviors. To address this, we examined the role of CGRP neurons in active defensive behavior using a predator-like robot programmed to chase mice. Our electrophysiological results revealed that CGRP neurons encode the intensity of aversive stimuli through variations in firing durations and amplitudes. Optogenetic activation of CGRP neurons during robot chasing elevated flight responses in both conditioning and retention tests, presumably by amplifying the perception of the threat as more imminent and dangerous. In contrast, animals with inactivated CGRP neurons exhibited reduced flight responses, even when the robot was programmed to appear highly threatening during conditioning. These findings expand the understanding of CGRP neurons in the PBN as a critical alarm system, capable of dynamically regulating active defensive behaviors by amplifying threat perception, and ensuring adaptive responses to varying levels of danger.