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Phelps JS, Hildebrand DGC, Graham BJ, Kuan AT, Thomas LA, Nguyen TM, Buhmann J, Azevedo AW, Sustar A, Agrawal S, Liu M, Shanny BL, Funke J, Tuthill JC, Lee WCA. Reconstruction of motor control circuits in adult Drosophila using automated transmission electron microscopy. Cell 2021; 184:759-774.e18. [PMID: 33400916 PMCID: PMC8312698 DOI: 10.1016/j.cell.2020.12.013] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 09/17/2020] [Accepted: 12/09/2020] [Indexed: 02/08/2023]
Abstract
To investigate circuit mechanisms underlying locomotor behavior, we used serial-section electron microscopy (EM) to acquire a synapse-resolution dataset containing the ventral nerve cord (VNC) of an adult female Drosophila melanogaster. To generate this dataset, we developed GridTape, a technology that combines automated serial-section collection with automated high-throughput transmission EM. Using this dataset, we studied neuronal networks that control leg and wing movements by reconstructing all 507 motor neurons that control the limbs. We show that a specific class of leg sensory neurons synapses directly onto motor neurons with the largest-caliber axons on both sides of the body, representing a unique pathway for fast limb control. We provide open access to the dataset and reconstructions registered to a standard atlas to permit matching of cells between EM and light microscopy data. We also provide GridTape instrumentation designs and software to make large-scale EM more accessible and affordable to the scientific community.
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Affiliation(s)
- Jasper S Phelps
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Program in Neuroscience, Division of Medical Sciences, Graduate School of Arts and Sciences, Harvard University, Cambridge, MA 02138, USA
| | - David Grant Colburn Hildebrand
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Program in Neuroscience, Division of Medical Sciences, Graduate School of Arts and Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Brett J Graham
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Aaron T Kuan
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Logan A Thomas
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Tri M Nguyen
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Julia Buhmann
- HHMI Janelia Research Campus, Ashburn, VA 20147, USA
| | - Anthony W Azevedo
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Anne Sustar
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Sweta Agrawal
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Mingguan Liu
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Brendan L Shanny
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jan Funke
- HHMI Janelia Research Campus, Ashburn, VA 20147, USA
| | - John C Tuthill
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Wei-Chung Allen Lee
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Namiki S, Dickinson MH, Wong AM, Korff W, Card GM. The functional organization of descending sensory-motor pathways in Drosophila. eLife 2018; 7:e34272. [PMID: 29943730 PMCID: PMC6019073 DOI: 10.7554/elife.34272] [Citation(s) in RCA: 161] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 05/09/2018] [Indexed: 12/12/2022] Open
Abstract
In most animals, the brain controls the body via a set of descending neurons (DNs) that traverse the neck. DN activity activates, maintains or modulates locomotion and other behaviors. Individual DNs have been well-studied in species from insects to primates, but little is known about overall connectivity patterns across the DN population. We systematically investigated DN anatomy in Drosophila melanogaster and created over 100 transgenic lines targeting individual cell types. We identified roughly half of all Drosophila DNs and comprehensively map connectivity between sensory and motor neuropils in the brain and nerve cord, respectively. We find the nerve cord is a layered system of neuropils reflecting the fly's capability for two largely independent means of locomotion -- walking and flight -- using distinct sets of appendages. Our results reveal the basic functional map of descending pathways in flies and provide tools for systematic interrogation of neural circuits.
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Affiliation(s)
- Shigehiro Namiki
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Michael H Dickinson
- Division of Biology and BioengineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Allan M Wong
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Wyatt Korff
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
| | - Gwyneth M Card
- Janelia Research Campus, Howard Hughes Medical InstituteAshburnUnited States
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Hsu CT, Bhandawat V. Organization of descending neurons in Drosophila melanogaster. Sci Rep 2016; 6:20259. [PMID: 26837716 PMCID: PMC4738306 DOI: 10.1038/srep20259] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/31/2015] [Indexed: 12/18/2022] Open
Abstract
Neural processing in the brain controls behavior through descending neurons (DNs) - neurons which carry signals from the brain to the spinal cord (or thoracic ganglia in insects). Because DNs arise from multiple circuits in the brain, the numerical simplicity and availability of genetic tools make Drosophila a tractable model for understanding descending motor control. As a first step towards a comprehensive study of descending motor control, here we estimate the number and distribution of DNs in the Drosophila brain. We labeled DNs by backfilling them with dextran dye applied to the neck connective and estimated that there are ~1100 DNs distributed in 6 clusters in Drosophila. To assess the distribution of DNs by neurotransmitters, we labeled DNs in flies in which neurons expressing the major neurotransmitters were also labeled. We found DNs belonging to every neurotransmitter class we tested: acetylcholine, GABA, glutamate, serotonin, dopamine and octopamine. Both the major excitatory neurotransmitter (acetylcholine) and the major inhibitory neurotransmitter (GABA) are employed equally; this stands in contrast to vertebrate DNs which are predominantly excitatory. By comparing the distribution of DNs in Drosophila to those reported previously in other insects, we conclude that the organization of DNs in insects is highly conserved.
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Affiliation(s)
- Cynthia T Hsu
- Department of Biology, Duke University, Durham, North Carolina 27708, USA.,Deparment of Neurobiology, Duke University, Durham, North Carolina 27708, USA
| | - Vikas Bhandawat
- Department of Biology, Duke University, Durham, North Carolina 27708, USA.,Deparment of Neurobiology, Duke University, Durham, North Carolina 27708, USA.,Duke Institute for Brain Sciences, Duke University, Durham, North Carolina 27708, USA
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Affiliation(s)
- Alexander Borst
- Department of Systems and Computational Neurobiology, Max-Planck-Institute of Neurobiology, Martinsried, Germany;
| | - Juergen Haag
- Department of Systems and Computational Neurobiology, Max-Planck-Institute of Neurobiology, Martinsried, Germany;
| | - Dierk F. Reiff
- Department of Systems and Computational Neurobiology, Max-Planck-Institute of Neurobiology, Martinsried, Germany;
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Abstract
Within the last 400 million years, insects have radiated into at least a million species, accounting for more than half of all known living organisms: they are the most successful group in the animal kingdom, found in almost all environments of the planet, ranging in body size from a mere 0.1 mm up to half a meter. Their eyes, together with the respective parts of the nervous system dedicated to the processing of visual information, have long been the subject of intense investigation but, with the exception of some very basic reflexes, it is still not possible to link an insect's visual input to its behavioral output. Fortunately for the field, the fruit fly Drosophila is an insect, too. This genetic workhorse holds great promise for the insect vision field, offering the possibility of recording, suppressing or stimulating any single neuron in its nervous system. Here, I shall give a brief synopsis of what we currently know about insect vision, describe the genetic toolset available in Drosophila and give some recent examples of how the application of these tools have furthered our understanding of color and motion vision in Drosophila.
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Affiliation(s)
- Alexander Borst
- Max-Planck-Institute for Neurobiology, Department of Systems and Computational Neurobiology, Martinsried, Germany.
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Sex-Specific Control and Tuning of the Pattern Generator for Courtship Song in Drosophila. Cell 2008; 133:354-63. [DOI: 10.1016/j.cell.2008.01.050] [Citation(s) in RCA: 237] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Revised: 12/05/2007] [Accepted: 01/29/2008] [Indexed: 11/23/2022]
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Bacon JP, Strausfeld NJ. The dipteran ?Giant fibre? pathway: neurons and signals. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1986. [DOI: 10.1007/bf00603798] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Benshalom G, Reese TS. Ultrastructural observations on the cytoarchitecture of axons processed by rapid-freezing and freeze-substitution. JOURNAL OF NEUROCYTOLOGY 1985; 14:943-60. [PMID: 2420942 DOI: 10.1007/bf01224806] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The structure and organization of axons in the cervical connective of wild-type Drosophila fruit flies were examined in anticipation of studies of various neurological mutants. Dissected flies were rapid-frozen from the living state against a copper block cooled with liquid helium, freeze-substituted, and prepared for electron microscopic examination of thin sections. These cryotechniques showed new details of the structure of cell organelles and cytoplasm in Drosophila axons. The cytoplasmic matrix of axons and glia consists of a material with a fine granular texture enmeshed in a three-dimensional meshwork of short, fine filaments which vary in shape, size and electron density. No neurofilaments are present, but bundles of microtubules are interwoven into the filamentous matrix of the axoplasm. The round wall of microtubules (27 nm overall diameter) is composed of twelve cylindrical protofilaments with a typical substructural periodicity. Mitochondria frequently make contact with microtubules in both axons and glial processes. A thin layer of electron-dense filamentous matrix, which appears to be an axonal basal lamina, contacts most of the axonal exoplasmic surface, especially that of axons where they are surrounded by processes of glial cells, but is scant wherever single axons are contiguous. Thus, an axonal basal lamina occupies the constricted spaces around axons, where extracellular K+ accumulates during neural activity.
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Abstract
Intracellular microelectrode recordings from the cervical giant fiber of normal Drosophila show a characteristic action potential waveform for this identified neuron. The action potential has a rapid initial spike followed by a prominent depolarizing afterpotential. Pharmacological experiments suggest that the giant fiber action potential depends on inward currents carried by Na+ and outward currents carried by K+. Abnormal action potentials are seen in Shaker (Sh) mutant Drosophila. This study compares the effects of six Sh alleles. In each case, abnormalities are limited to action potential repolarization. There are, however, allelic differences. Five alleles cause delayed repolarization and increased action potential durations. Going from most to least extreme, these alleles are: Sh102 greater than ShKS133 greater than ShM greater than ShE62 greater than ShrKO120. Compared to normal action potentials, durations in the extreme mutants are longer by an order of magnitude or more. One mutant allele, Sh5 appears to cause an incompletely repolarized action potential, rather than a repolarization delay.
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Benshalom G, Dagan D. Drosophila neural pathways. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 1985. [DOI: 10.1007/bf00610662] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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King DG, Valentino KL. On neuronal homology: a comparison of similar axons in Musca, Sarcophaga, and Drosophila (Diptera: Schizophora). J Comp Neurol 1983; 219:1-9. [PMID: 6619326 DOI: 10.1002/cne.902190102] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Thoracic axons occurring in Musca and Sarcophaga are similar to those previously reported in the giant fiber pathway of Drosophila. Serial section reconstruction of both species has shown that the cervical giant fiber descending from the brain into the thoracic ganglion and the thoracic motor axon innervating the tergotrochanteral muscle follow courses matching those of similar axons in Drosophila. Likewise in both Musca and Sarcophaga a thoracic axon establishes axoaxonal synapses onto dorsal longitudinal muscle motor neurons. This axon is similar in both course and synaptic configuration to the peripherally synapsing interneuron in Drosophila. Although these similarities suggest that the three axon pairs are homologous in all three fly species, Several differences are also observed. Thus this system of identified axons may be a useful model for investigating phylogenetic variation in specific neuronal form and connectivity.
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King DG. Evolutionary loss of a neural pathway from the nervous system of a fly (Glossina morsitans/Diptera). J Morphol 1983; 175:27-32. [DOI: 10.1002/jmor.1051750104] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Thomas JB, Wyman RJ. Normal and mutant connectivity between identified neurons in Drosophila. Trends Neurosci 1983. [DOI: 10.1016/0166-2236(83)90097-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Koto M, Tanouye MA, Ferrus A, Thomas JB, Wyman RJ. The morphology of the cervical giant fiber neuron of Drosophila. Brain Res 1981; 221:213-7. [PMID: 6793208 DOI: 10.1016/0006-8993(81)90772-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The morphology of the cervical giant fiber (CGF) neuron of Drosophila melanogaster was studied by intracellular injection of Lucifer yellow dye. The CGF neuron is the command cell in a motor circuit causing visually driven escape behavior: a single action potential in a CGF axon produces patterned activity in jump and flight muscles. The present study identified the CGF cell body, a large soma located in the posterior part of the lower ipsilateral protocerebrum. The main process runs anteriorly from the cell body, extends three branches, and turns posteromedially while descending through the brain. The CGF axon courses through the cervical connective and ends within the mesothoracic neuromere of the thoracic ganglion. Thus, the CGF neuron is an interneuron, not a motoneuron as previously believed. We have been isolating mutants that affect CGF neuron-mediated behavior. Comparison of CGF neuron morphology in wildtype strains with that in these mutants will allow identification of genes that affect the development, structure, and connections of the CGF neuron.
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King DG, Wyman RJ. Anatomy of the giant fibre pathway in Drosophila. I. Three thoracic components of the pathway. JOURNAL OF NEUROCYTOLOGY 1980; 9:753-70. [PMID: 6782199 DOI: 10.1007/bf01205017] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Activity in the flight muscles and jump muscles in Drosophila can be stimulated by excitation of a pair of giant fibres that enter the thoracic ganglion from the brain. Contrary to previous descriptions, these giant fibres are not themselves motor axons. Each giant fibre contacts both a large motor axon and an interneuron. The motor axon innervates the ipsilateral tergotrochanteral (jump) muscle. The interneuron synapses in turn with the motor neurons that innervate the contralateral dorsal longitudinal flight muscle. The output synapses of this interneuron occur directly onto the motor axons within a peripheral nerve. The unusual peripheral location for these interneuron synapses suggests that the interneuron may function to speed up activation of the motor axons by bypassing integration within the motor neurons' dendritic trees. The synapses are typical dipteran chemical synapses, with occasional reciprocal contacts from the motor axons back onto the interneuron. The interneuron-motor axon synapses may be especially useful for morphological studies of identified synaptic contacts because their peripheral location makes them extremely easy to locate and identify.
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RICE MJ, WEBB PD. GIANT AXONS IN THE CENTRAL NERVOUS SYSTEM OF CTENOMORPHODES TESSULATUS (GRAY), AN AUSTRALIAN STICK INSECT. ACTA ACUST UNITED AC 1975. [DOI: 10.1111/j.1440-6055.1975.tb02042.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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