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Bonanno SL, Krantz DE. Transcriptional changes in specific subsets of Drosophila neurons following inhibition of the serotonin transporter. Transl Psychiatry 2023; 13:226. [PMID: 37355701 DOI: 10.1038/s41398-023-02521-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/06/2023] [Accepted: 06/13/2023] [Indexed: 06/26/2023] Open
Abstract
The transcriptional effects of SSRIs and other serotonergic drugs remain unclear, in part due to the heterogeneity of postsynaptic cells, which may respond differently to changes in serotonergic signaling. Relatively simple model systems such as Drosophila afford more tractable microcircuits in which to investigate these changes in specific cell types. Here, we focus on the mushroom body, an insect brain structure heavily innervated by serotonin and comprised of multiple different but related subtypes of Kenyon cells. We use fluorescence-activated cell sorting of Kenyon cells, followed by either bulk or single-cell RNA sequencing to explore the transcriptomic response of these cells to SERT inhibition. We compared the effects of two different Drosophila Serotonin Transporter (dSERT) mutant alleles as well as feeding the SSRI citalopram to adult flies. We find that the genetic architecture associated with one of the mutants contributed to significant artefactual changes in expression. Comparison of differential expression caused by loss of SERT during development versus aged, adult flies, suggests that changes in serotonergic signaling may have relatively stronger effects during development, consistent with behavioral studies in mice. Overall, our experiments revealed limited transcriptomic changes in Kenyon cells, but suggest that different subtypes may respond differently to SERT loss-of-function. Further work exploring the effects of SERT loss-of-function in other circuits may be used help to elucidate how SSRIs differentially affect a variety of different neuronal subtypes both during development and in adults.
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Affiliation(s)
- Shivan L Bonanno
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA
| | - David E Krantz
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, 90095, USA.
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2
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Bonanno SL, Krantz DE. Transcriptional changes in specific subsets of Drosophila neurons following inhibition of the serotonin transporter. RESEARCH SQUARE 2023:rs.3.rs-2626506. [PMID: 36993644 PMCID: PMC10055553 DOI: 10.21203/rs.3.rs-2626506/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The transcriptional effects of SSRIs and other serotonergic drugs remain unclear, in part due to the heterogeneity of postsynaptic cells, which may respond differently to changes in serotonergic signaling. Relatively simple model systems such as Drosophila afford more tractable microcircuits in which to investigate these changes in specific cell types. Here, we focus on the mushroom body, an insect brain structure heavily innervated by serotonin and comprised of multiple different but related subtypes of Kenyon cells. We use fluorescence activated cell sorting of Kenyon cells, followed by either or bulk or single cell RNA sequencing to explore the transcriptomic response of these cells to SERT inhibition. We compared the effects of two different Drosophila Serotonin Transporter (dSERT) mutant alleles as well as feeding the SSRI citalapram to adult flies. We find that the genetic architecture associated with one of the mutants contributed to significant artefactual changes in expression. Comparison of differential expression caused by loss of SERT during development versus aged, adult flies, suggests that changes in serotonergic signaling may have relatively stronger effects during development, consistent with behavioral studies in mice. Overall, our experiments revealed limited transcriptomic changes in Kenyon cells, but suggest that different subtypes may respond differently to SERT loss-of-function. Further work exploring the effects of SERT loss-of-function in other Drosophila circuits may be used help to elucidate how SSRIs differentially affect a variety of different neuronal subtypes both during development and in adults.
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Affiliation(s)
- Shivan L. Bonanno
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - David E. Krantz
- Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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3
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Truman JW, Riddiford LM. Drosophila postembryonic nervous system development: a model for the endocrine control of development. Genetics 2023; 223:iyac184. [PMID: 36645270 PMCID: PMC9991519 DOI: 10.1093/genetics/iyac184] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/13/2022] [Indexed: 01/17/2023] Open
Abstract
During postembryonic life, hormones, including ecdysteroids, juvenile hormones, insulin-like peptides, and activin/TGFβ ligands act to transform the larval nervous system into an adult version, which is a fine-grained mosaic of recycled larval neurons and adult-specific neurons. Hormones provide both instructional signals that make cells competent to undergo developmental change and timing cues to evoke these changes across the nervous system. While touching on all the above hormones, our emphasis is on the ecdysteroids, ecdysone and 20-hydroxyecdysone (20E). These are the prime movers of insect molting and metamorphosis and are involved in all phases of nervous system development, including neurogenesis, pruning, arbor outgrowth, and cell death. Ecdysteroids appear as a series of steroid peaks that coordinate the larval molts and the different phases of metamorphosis. Each peak directs a stereotyped cascade of transcription factor expression. The cascade components then direct temporal programs of effector gene expression, but the latter vary markedly according to tissue and life stage. The neurons read the ecdysteroid titer through various isoforms of the ecdysone receptor, a nuclear hormone receptor. For example, at metamorphosis the pruning of larval neurons is mediated through the B isoforms, which have strong activation functions, whereas subsequent outgrowth is mediated through the A isoform through which ecdysteroids play a permissive role to allow local tissue interactions to direct outgrowth. The major circulating ecdysteroid can also change through development. During adult development ecdysone promotes early adult patterning and differentiation while its metabolite, 20E, later evokes terminal adult differentiation.
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Affiliation(s)
- James W Truman
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA
| | - Lynn M Riddiford
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA
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4
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Truman JW, Price J, Miyares RL, Lee T. Metamorphosis of memory circuits in Drosophila reveals a strategy for evolving a larval brain. eLife 2023; 12:80594. [PMID: 36695420 PMCID: PMC9984194 DOI: 10.7554/elife.80594] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 01/24/2023] [Indexed: 01/26/2023] Open
Abstract
Mushroom bodies (MB) of adult Drosophila have a core of thousands of Kenyon neurons; axons of the early-born g class form a medial lobe and those from later-born α'β' and αβ classes form both medial and vertical lobes. The larva, however, hatches with only γ neurons and forms a vertical lobe 'facsimile' using larval-specific axon branches from its γ neurons. MB input (MBINs) and output (MBONs) neurons divide the Kenyon neuron lobes into discrete computational compartments. The larva has 10 such compartments while the adult has 16. We determined the fates of 28 of the 32 MBONs and MBINs that define the 10 larval compartments. Seven compartments are subsequently incorporated into the adult MB; four of their MBINs die, while 12 MBINs/MBONs remodel to function in adult compartments. The remaining three compartments are larval specific. At metamorphosis their MBIN/MBONs trans-differentiate, leaving the MB for other adult brain circuits. The adult vertical lobes are made de novo using MBONs/MBINs recruited from pools of adult-specific neurons. The combination of cell death, compartment shifting, trans-differentiation, and recruitment of new neurons result in no larval MBIN-MBON connections being maintained through metamorphosis. At this simple level, then, we find no anatomical substrate for a memory trace persisting from larva to adult. The adult phenotype of the trans-differentiating neurons represents their evolutionarily ancestral phenotype while their larval phenotype is a derived adaptation for the larval stage. These cells arise primarily within lineages that also produce permanent MBINs and MBONs, suggesting that larval specifying factors may allow information related to birth-order or sibling identity to be interpreted in a modified manner in the larva to allow these neurons to acquire larval phenotypic modifications. The loss of such factors at metamorphosis then allows these neurons to revert to their ancestral functions in the adult.
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Affiliation(s)
- James W Truman
- Janelia Research CampusAshburnUnited States
- Department of Biology, Friday Harbor Laboratories, University of WashingtonFriday HarborUnited States
| | | | | | - Tzumin Lee
- Janelia Research CampusAshburnUnited States
- Life Sciences Institute, University of MichiganAnn ArborUnited States
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5
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Koreman GT, Xu Y, Hu Q, Zhang Z, Allen SE, Wolfner MF, Wang B, Han C. Upgraded CRISPR/Cas9 tools for tissue-specific mutagenesis in Drosophila. Proc Natl Acad Sci U S A 2021; 118:e2014255118. [PMID: 33782117 PMCID: PMC8040800 DOI: 10.1073/pnas.2014255118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
CRISPR/Cas9 has emerged as a powerful technology for tissue-specific mutagenesis. However, tissue-specific CRISPR/Cas9 tools currently available in Drosophila remain deficient in three significant ways. First, many existing gRNAs are inefficient, such that further improvements of gRNA expression constructs are needed for more efficient and predictable mutagenesis in both somatic and germline tissues. Second, it has been difficult to label mutant cells in target tissues with current methods. Lastly, application of tissue-specific mutagenesis at present often relies on Gal4-driven Cas9, which hampers the flexibility and effectiveness of the system. Here, we tackle these deficiencies by building upon our previous CRISPR-mediated tissue-restricted mutagenesis (CRISPR-TRiM) tools. First, we significantly improved gRNA efficiency in somatic tissues by optimizing multiplexed gRNA design. Similarly, we also designed efficient dual-gRNA vectors for the germline. Second, we developed methods to positively and negatively label mutant cells in tissue-specific mutagenesis by incorporating co-CRISPR reporters into gRNA expression vectors. Lastly, we generated genetic reagents for convenient conversion of existing Gal4 drivers into tissue-specific Cas9 lines based on homology-assisted CRISPR knock-in. In this way, we expand the choices of Cas9 for CRISPR-TRiM analysis to broader tissues and developmental stages. Overall, our upgraded CRISPR/Cas9 tools make tissue-specific mutagenesis more versatile, reliable, and effective in Drosophila These improvements may be also applied to other model systems.
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Affiliation(s)
- Gabriel T Koreman
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Yineng Xu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Qinan Hu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Zijing Zhang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Sarah E Allen
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Bei Wang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853;
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Chun Han
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853;
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
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6
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Perez-Catalan NA, Doe CQ, Ackerman SD. The role of astrocyte-mediated plasticity in neural circuit development and function. Neural Dev 2021; 16:1. [PMID: 33413602 PMCID: PMC7789420 DOI: 10.1186/s13064-020-00151-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/26/2020] [Indexed: 02/03/2023] Open
Abstract
Neuronal networks are capable of undergoing rapid structural and functional changes called plasticity, which are essential for shaping circuit function during nervous system development. These changes range from short-term modifications on the order of milliseconds, to long-term rearrangement of neural architecture that could last for the lifetime of the organism. Neural plasticity is most prominent during development, yet also plays a critical role during memory formation, behavior, and disease. Therefore, it is essential to define and characterize the mechanisms underlying the onset, duration, and form of plasticity. Astrocytes, the most numerous glial cell type in the human nervous system, are integral elements of synapses and are components of a glial network that can coordinate neural activity at a circuit-wide level. Moreover, their arrival to the CNS during late embryogenesis correlates to the onset of sensory-evoked activity, making them an interesting target for circuit plasticity studies. Technological advancements in the last decade have uncovered astrocytes as prominent regulators of circuit assembly and function. Here, we provide a brief historical perspective on our understanding of astrocytes in the nervous system, and review the latest advances on the role of astroglia in regulating circuit plasticity and function during nervous system development and homeostasis.
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Affiliation(s)
- Nelson A Perez-Catalan
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, USA
- Kennedy Center, Department of Pediatrics, The University of Chicago, Chicago, IL, USA
| | - Chris Q Doe
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, USA
| | - Sarah D Ackerman
- Institute of Neuroscience, Howard Hughes Medical Institute, University of Oregon, Eugene, OR, USA.
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Vogt K, Zimmerman DM, Schlichting M, Hernandez-Nunez L, Qin S, Malacon K, Rosbash M, Pehlevan C, Cardona A, Samuel ADT. Internal state configures olfactory behavior and early sensory processing in Drosophila larvae. SCIENCE ADVANCES 2021; 7:7/1/eabd6900. [PMID: 33523854 PMCID: PMC7775770 DOI: 10.1126/sciadv.abd6900] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 11/04/2020] [Indexed: 05/07/2023]
Abstract
Animals exhibit different behavioral responses to the same sensory cue depending on their internal state at a given moment. How and where in the brain are sensory inputs combined with state information to select an appropriate behavior? Here, we investigate how food deprivation affects olfactory behavior in Drosophila larvae. We find that certain odors repel well-fed animals but attract food-deprived animals and that feeding state flexibly alters neural processing in the first olfactory center, the antennal lobe. Hunger differentially modulates two output pathways required for opposing behavioral responses. Upon food deprivation, attraction-mediating uniglomerular projection neurons show elevated odor-evoked activity, whereas an aversion-mediating multiglomerular projection neuron receives odor-evoked inhibition. The switch between these two pathways is regulated by the lone serotonergic neuron in the antennal lobe, CSD. Our findings demonstrate how flexible behaviors can arise from state-dependent circuit dynamics in an early sensory processing center.
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Affiliation(s)
- Katrin Vogt
- Department of Physics, Harvard University, Cambridge, MA 02138, USA.
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - David M Zimmerman
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
- Harvard Graduate Program in Biophysics, Harvard University, Cambridge, MA 02138, USA
| | - Matthias Schlichting
- Department of Biology, Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454, USA
| | - Luis Hernandez-Nunez
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
- Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Shanshan Qin
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Karen Malacon
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Michael Rosbash
- Department of Biology, Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454, USA
| | - Cengiz Pehlevan
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Albert Cardona
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK
| | - Aravinthan D T Samuel
- Department of Physics, Harvard University, Cambridge, MA 02138, USA.
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
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8
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Chvilicek MM, Titos I, Rothenfluh A. The Neurotransmitters Involved in Drosophila Alcohol-Induced Behaviors. Front Behav Neurosci 2020; 14:607700. [PMID: 33384590 PMCID: PMC7770116 DOI: 10.3389/fnbeh.2020.607700] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Abstract
Alcohol is a widely used and abused substance with numerous negative consequences for human health and safety. Historically, alcohol's widespread, non-specific neurobiological effects have made it a challenge to study in humans. Therefore, model organisms are a critical tool for unraveling the mechanisms of alcohol action and subsequent effects on behavior. Drosophila melanogaster is genetically tractable and displays a vast behavioral repertoire, making it a particularly good candidate for examining the neurobiology of alcohol responses. In addition to being experimentally amenable, Drosophila have high face and mechanistic validity: their alcohol-related behaviors are remarkably consistent with humans and other mammalian species, and they share numerous conserved neurotransmitters and signaling pathways. Flies have a long history in alcohol research, which has been enhanced in recent years by the development of tools that allow for manipulating individual Drosophila neurotransmitters. Through advancements such as the GAL4/UAS system and CRISPR/Cas9 mutagenesis, investigation of specific neurotransmitters in small subsets of neurons has become ever more achievable. In this review, we describe recent progress in understanding the contribution of seven neurotransmitters to fly behavior, focusing on their roles in alcohol response: dopamine, octopamine, tyramine, serotonin, glutamate, GABA, and acetylcholine. We chose these small-molecule neurotransmitters due to their conservation in mammals and their importance for behavior. While neurotransmitters like dopamine and octopamine have received significant research emphasis regarding their contributions to behavior, others, like glutamate, GABA, and acetylcholine, remain relatively unexplored. Here, we summarize recent genetic and behavioral findings concerning these seven neurotransmitters and their roles in the behavioral response to alcohol, highlighting the fitness of the fly as a model for human alcohol use.
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Affiliation(s)
- Maggie M. Chvilicek
- Department of Psychiatry, University of Utah, Salt Lake City, UT, United States
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, United States
- Neuroscience Graduate Program, University of Utah, Salt Lake City, UT, United States
| | - Iris Titos
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, United States
| | - Adrian Rothenfluh
- Department of Psychiatry, University of Utah, Salt Lake City, UT, United States
- Molecular Medicine Program, University of Utah, Salt Lake City, UT, United States
- Neuroscience Graduate Program, University of Utah, Salt Lake City, UT, United States
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, United States
- Department of Human Genetics, University of Utah, Salt Lake City, UT, United States
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9
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Honegger KS, Smith MAY, Churgin MA, Turner GC, de Bivort BL. Idiosyncratic neural coding and neuromodulation of olfactory individuality in Drosophila. Proc Natl Acad Sci U S A 2020; 117:23292-23297. [PMID: 31455738 PMCID: PMC7519279 DOI: 10.1073/pnas.1901623116] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Innate behavioral biases and preferences can vary significantly among individuals of the same genotype. Though individuality is a fundamental property of behavior, it is not currently understood how individual differences in brain structure and physiology produce idiosyncratic behaviors. Here we present evidence for idiosyncrasy in olfactory behavior and neural responses in Drosophila We show that individual female Drosophila from a highly inbred laboratory strain exhibit idiosyncratic odor preferences that persist for days. We used in vivo calcium imaging of neural responses to compare projection neuron (second-order neurons that convey odor information from the sensory periphery to the central brain) responses to the same odors across animals. We found that, while odor responses appear grossly stereotyped, upon closer inspection, many individual differences are apparent across antennal lobe (AL) glomeruli (compact microcircuits corresponding to different odor channels). Moreover, we show that neuromodulation, environmental stress in the form of altered nutrition, and activity of certain AL local interneurons affect the magnitude of interfly behavioral variability. Taken together, this work demonstrates that individual Drosophila exhibit idiosyncratic olfactory preferences and idiosyncratic neural responses to odors, and that behavioral idiosyncrasies are subject to neuromodulation and regulation by neurons in the AL.
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Affiliation(s)
- Kyle S Honegger
- Department of Organismic and Evolutionary Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138
- Computational Informatics and Visualization Laboratory, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611
| | - Matthew A-Y Smith
- Department of Organismic and Evolutionary Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138
| | - Matthew A Churgin
- Department of Organismic and Evolutionary Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138
| | - Glenn C Turner
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | - Benjamin L de Bivort
- Department of Organismic and Evolutionary Biology and Center for Brain Science, Harvard University, Cambridge, MA 02138;
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10
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Coates KE, Calle-Schuler SA, Helmick LM, Knotts VL, Martik BN, Salman F, Warner LT, Valla SV, Bock DD, Dacks AM. The Wiring Logic of an Identified Serotonergic Neuron That Spans Sensory Networks. J Neurosci 2020; 40:6309-6327. [PMID: 32641403 PMCID: PMC7424878 DOI: 10.1523/jneurosci.0552-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/16/2020] [Accepted: 06/25/2020] [Indexed: 12/21/2022] Open
Abstract
Serotonergic neurons project widely throughout the brain to modulate diverse physiological and behavioral processes. However, a single-cell resolution understanding of the connectivity of serotonergic neurons is currently lacking. Using a whole-brain EM dataset of a female Drosophila, we comprehensively determine the wiring logic of a broadly projecting serotonergic neuron (the CSDn) that spans several olfactory regions. Within the antennal lobe, the CSDn differentially innervates each glomerulus, yet surprisingly, this variability reflects a diverse set of presynaptic partners, rather than glomerulus-specific differences in synaptic output, which is predominately to local interneurons. Moreover, the CSDn has distinct connectivity relationships with specific local interneuron subtypes, suggesting that the CSDn influences distinct aspects of local network processing. Across olfactory regions, the CSDn has different patterns of connectivity, even having different connectivity with individual projection neurons that also span these regions. Whereas the CSDn targets inhibitory local neurons in the antennal lobe, the CSDn has more distributed connectivity in the LH, preferentially synapsing with principal neuron types based on transmitter content. Last, we identify individual novel synaptic partners associated with other sensory domains that provide strong, top-down input to the CSDn. Together, our study reveals the complex connectivity of serotonergic neurons, which combine the integration of local and extrinsic synaptic input in a nuanced, region-specific manner.SIGNIFICANCE STATEMENT All sensory systems receive serotonergic modulatory input. However, a comprehensive understanding of the synaptic connectivity of individual serotonergic neurons is lacking. In this study, we use a whole-brain EM microscopy dataset to comprehensively determine the wiring logic of a broadly projecting serotonergic neuron in the olfactory system of Drosophila Collectively, our study demonstrates, at a single-cell level, the complex connectivity of serotonergic neurons within their target networks, identifies specific cell classes heavily targeted for serotonergic modulation in the olfactory system, and reveals novel extrinsic neurons that provide strong input to this serotonergic system outside of the context of olfaction. Elucidating the connectivity logic of individual modulatory neurons provides a ground plan for the seemingly heterogeneous effects of modulatory systems.
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Affiliation(s)
- Kaylynn E Coates
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
| | | | - Levi M Helmick
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
| | - Victoria L Knotts
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
| | - Brennah N Martik
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
| | - Farzaan Salman
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
| | - Lauren T Warner
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
| | - Sophia V Valla
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
| | - Davi D Bock
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, West Virginia 26506
- Department of Neuroscience, West Virginia University, Morgantown, West Virginia 26506
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11
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Ancestral regulatory mechanisms specify conserved midbrain circuitry in arthropods and vertebrates. Proc Natl Acad Sci U S A 2020; 117:19544-19555. [PMID: 32747566 PMCID: PMC7431035 DOI: 10.1073/pnas.1918797117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Comparative developmental genetics indicate insect and mammalian forebrains form and function in comparable ways. However, these data are open to opposing interpretations that advocate either a single origin of the brain and its adaptive modification during animal evolution; or multiple, independent origins of the many different brains present in extant Bilateria. Here, we describe conserved regulatory elements that mediate the spatiotemporal expression of developmental control genes directing the formation and function of midbrain circuits in flies, mice, and humans. These circuits develop from corresponding midbrain-hindbrain boundary regions and regulate comparable behaviors for balance and motor control. Our findings suggest that conserved regulatory mechanisms specify cephalic circuits for sensory integration and coordinated behavior common to all animals that possess a brain. Corresponding attributes of neural development and function suggest arthropod and vertebrate brains may have an evolutionarily conserved organization. However, the underlying mechanisms have remained elusive. Here, we identify a gene regulatory and character identity network defining the deutocerebral–tritocerebral boundary (DTB) in Drosophila. This network comprises genes homologous to those directing midbrain-hindbrain boundary (MHB) formation in vertebrates and their closest chordate relatives. Genetic tracing reveals that the embryonic DTB gives rise to adult midbrain circuits that in flies control auditory and vestibular information processing and motor coordination, as do MHB-derived circuits in vertebrates. DTB-specific gene expression and function are directed by cis-regulatory elements of developmental control genes that include homologs of mammalian Zinc finger of the cerebellum and Purkinje cell protein 4. Drosophila DTB-specific cis-regulatory elements correspond to regulatory sequences of human ENGRAILED-2, PAX-2, and DACHSHUND-1 that direct MHB-specific expression in the embryonic mouse brain. We show that cis-regulatory elements and the gene networks they regulate direct the formation and function of midbrain circuits for balance and motor coordination in insects and mammals. Regulatory mechanisms mediating the genetic specification of cephalic neural circuits in arthropods correspond to those in chordates, thereby implying their origin before the divergence of deuterostomes and ecdysozoans.
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12
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Hidalgo S, Fuenzalida-Uribe N, Molina-Mateo D, Escobar AP, Oliva C, España RA, Andrés ME, Campusano JM. Study of the release of endogenous amines in Drosophila brain in vivo in response to stimuli linked to aversive olfactory conditioning. J Neurochem 2020; 156:337-351. [PMID: 32596813 DOI: 10.1111/jnc.15109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 11/27/2022]
Abstract
A highly challenging question in neuroscience is to understand how aminergic neural circuits contribute to the planning and execution of behaviors, including the generation of olfactory memories. In this regard, electrophysiological techniques like Local Field Potential or imaging methods have been used to answer questions relevant to cell and circuit physiology in different animal models, such as the fly Drosophila melanogaster. However, these techniques do not provide information on the neurochemical identity of the circuits of interest. Different approaches including fast scan cyclic voltammetry, allow researchers to identify and quantify in a timely fashion the release of endogenous neuroactive molecules, but have been only used in in vitro Drosophila brain preparations. Here, we report a procedure to record for the first time the release of endogenous amines -dopamine, serotonin and octopamine- in adult fly brain in vivo, by fast scan cyclic voltammetry. As a proof of principle, we carried out recordings in the calyx region of the Mushroom Bodies, the brain area mainly associated to the generation of olfactory memories in flies. By using principal component regression in normalized training sets for in vivo recordings, we detect an increase in octopamine and serotonin levels in response to electric shock and olfactory cues respectively. This new approach allows the study of dynamic changes in amine neurotransmission that underlie complex behaviors in Drosophila and shed new light on the contribution of these amines to olfactory processing in this animal model.
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Affiliation(s)
- Sergio Hidalgo
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,School of Physiology, Pharmacology and Ncxeuroscience, Faculty of Life Sciences, University of Bristol, Bristol, UK
| | - Nicolás Fuenzalida-Uribe
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniela Molina-Mateo
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Angélica P Escobar
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carlos Oliva
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rodrigo A España
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Maria Estela Andrés
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jorge M Campusano
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro Interdisciplinario de Neurociencia UC, Santiago, Chile
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13
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Sizemore TR, Hurley LM, Dacks AM. Serotonergic modulation across sensory modalities. J Neurophysiol 2020; 123:2406-2425. [PMID: 32401124 PMCID: PMC7311732 DOI: 10.1152/jn.00034.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/04/2020] [Accepted: 05/12/2020] [Indexed: 12/24/2022] Open
Abstract
The serotonergic system has been widely studied across animal taxa and different functional networks. This modulatory system is therefore well positioned to compare the consequences of neuromodulation for sensory processing across species and modalities at multiple levels of sensory organization. Serotonergic neurons that innervate sensory networks often bidirectionally exchange information with these networks but also receive input representative of motor events or motivational state. This convergence of information supports serotonin's capacity for contextualizing sensory information according to the animal's physiological state and external events. At the level of sensory circuitry, serotonin can have variable effects due to differential projections across specific sensory subregions, as well as differential serotonin receptor type expression within those subregions. Functionally, this infrastructure may gate or filter sensory inputs to emphasize specific stimulus features or select among different streams of information. The near-ubiquitous presence of serotonin and other neuromodulators within sensory regions, coupled with their strong effects on stimulus representation, suggests that these signaling pathways should be considered integral components of sensory systems.
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Affiliation(s)
- Tyler R Sizemore
- Department of Biology, West Virginia University, Morgantown, West Virginia
| | - Laura M Hurley
- Department of Biology, Indiana University, Bloomington, Indiana
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, West Virginia
- Department of Neuroscience, West Virginia University, Morgantown, West Virginia
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14
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Serotonin transporter dependent modulation of food-seeking behavior. PLoS One 2020; 15:e0227554. [PMID: 31978073 PMCID: PMC6980608 DOI: 10.1371/journal.pone.0227554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 12/20/2019] [Indexed: 11/28/2022] Open
Abstract
The olfactory pathway integrates the odor information required to generate correct behavioral responses. To address how changes of serotonin signaling in two contralaterally projecting, serotonin-immunoreactive deutocerebral neurons impacts key odorant attraction in Drosophila melanogaster, we selectively alter serotonin signaling using the serotonin transporter with mutated serotonin binding sites in these neurons and analyzed the consequence on odorant-guided food seeking. The expression of the mutated serotonin transporter selectively changed the odorant attraction in an odorant-specific manner. The shift in attraction was not influenced by more up-stream serotonergic mechanisms mediating behavioral inhibition. The expression of the mutated serotonin transporter in CSD neurons did not influence other behaviors associated with food seeking such as olfactory learning and memory or food consumption. We provide evidence that the change in the attraction by serotonin transporter function might be achieved by increased serotonin signaling and by different serotonin receptors. The 5-HT1B receptor positively regulated the attraction to low and negatively regulated the attraction to high concentrations of acetic acid. In contrast, 5-HT1A and 5-HT2A receptors negatively regulated the attraction in projection neurons to high acetic acid concentrations. These results provide insights into how serotonin signaling in two serotonergic neurons selectively regulates the behavioral response to key odorants during food seeking.
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15
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Bridi JC, Ludlow ZN, Hirth F. Lineage-specific determination of ring neuron circuitry in the central complex of Drosophila. Biol Open 2019; 8:bio.045062. [PMID: 31285267 PMCID: PMC6679397 DOI: 10.1242/bio.045062] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The ellipsoid body (EB) of the Drosophila central complex mediates sensorimotor integration and action selection for adaptive behaviours. Insights into its physiological function are steadily accumulating, however the developmental origin and genetic specification have remained largely elusive. Here we identify two stem cells in the embryonic neuroectoderm as precursor cells of neuronal progeny that establish EB circuits in the adult brain. Genetic tracing of embryonic neuroblasts ppd5 and mosaic analysis with a repressible cell marker identified lineage-related progeny as Pox neuro (Poxn)-expressing EB ring neurons, R1-R4. During embryonic brain development, engrailed function is required for the initial formation of Poxn-expressing ppd5-derived progeny. Postembryonic determination of R1-R4 identity depends on lineage-specific Poxn function that separates neuronal subtypes of ppd5-derived progeny into hemi-lineages with projections either terminating in the EB ring neuropil or the superior protocerebrum (SP). Poxn knockdown in ppd5-derived progeny results in identity transformation of engrailed-expressing hemi-lineages from SP to EB-specific circuits. In contrast, lineage-specific knockdown of engrailed leads to reduced numbers of Poxn-expressing ring neurons. These findings establish neuroblasts ppd5-derived ring neurons as lineage-related sister cells that require engrailed and Poxn function for the proper formation of EB circuitry in the adult central complex of Drosophila.
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Affiliation(s)
- Jessika C Bridi
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9RX, United Kingdom
| | - Zoe N Ludlow
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9RX, United Kingdom
| | - Frank Hirth
- Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 9RX, United Kingdom
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16
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Zhang X, Coates K, Dacks A, Günay C, Lauritzen JS, Li F, Calle-Schuler SA, Bock D, Gaudry Q. Local synaptic inputs support opposing, network-specific odor representations in a widely projecting modulatory neuron. eLife 2019; 8:46839. [PMID: 31264962 PMCID: PMC6660217 DOI: 10.7554/elife.46839] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/01/2019] [Indexed: 12/14/2022] Open
Abstract
Serotonin plays different roles across networks within the same sensory modality. Previously, we used whole-cell electrophysiology in Drosophila to show that serotonergic neurons innervating the first olfactory relay are inhibited by odorants (Zhang and Gaudry, 2016). Here we show that network-spanning serotonergic neurons segregate information about stimulus features, odor intensity and identity, by using opposing coding schemes in different olfactory neuropil. A pair of serotonergic neurons (the CSDns) innervate the antennal lobe and lateral horn, which are first and second order neuropils. CSDn processes in the antennal lobe are inhibited by odors in an identity independent manner. In the lateral horn, CSDn processes are excited in an odor identity dependent manner. Using functional imaging, modeling, and EM reconstruction, we demonstrate that antennal lobe derived inhibition arises from local GABAergic inputs and acts as a means of gain control on branch-specific inputs that the CSDns receive within the lateral horn.
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Affiliation(s)
- Xiaonan Zhang
- Department of Biology, University of Maryland, College Park, United States
| | - Kaylynn Coates
- Department of Biology, West Virginia University, Morgantown, United States
| | - Andrew Dacks
- Department of Biology, West Virginia University, Morgantown, United States
| | - Cengiz Günay
- School of Science and Technology, Georgia Gwinnett College, Lawrenceville, United States
| | - J Scott Lauritzen
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Feng Li
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | | | - Davi Bock
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States.,Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, United States
| | - Quentin Gaudry
- Department of Biology, University of Maryland, College Park, United States
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17
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Frechter S, Bates AS, Tootoonian S, Dolan MJ, Manton J, Jamasb AR, Kohl J, Bock D, Jefferis G. Functional and anatomical specificity in a higher olfactory centre. eLife 2019; 8:44590. [PMID: 31112127 PMCID: PMC6550879 DOI: 10.7554/elife.44590] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/12/2019] [Indexed: 12/16/2022] Open
Abstract
Most sensory systems are organized into parallel neuronal pathways that process distinct aspects of incoming stimuli. In the insect olfactory system, second order projection neurons target both the mushroom body, required for learning, and the lateral horn (LH), proposed to mediate innate olfactory behavior. Mushroom body neurons form a sparse olfactory population code, which is not stereotyped across animals. In contrast, odor coding in the LH remains poorly understood. We combine genetic driver lines, anatomical and functional criteria to show that the Drosophila LH has ~1400 neurons and >165 cell types. Genetically labeled LHNs have stereotyped odor responses across animals and on average respond to three times more odors than single projection neurons. LHNs are better odor categorizers than projection neurons, likely due to stereotyped pooling of related inputs. Our results reveal some of the principles by which a higher processing area can extract innate behavioral significance from sensory stimuli.
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Affiliation(s)
- Shahar Frechter
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - Sina Tootoonian
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.,Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Michael-John Dolan
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Janelia Research Campus, Howard Hughes Medical Institute, Chevy Chase, United States
| | - James Manton
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - Johannes Kohl
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Davi Bock
- Janelia Research Campus, Howard Hughes Medical Institute, Chevy Chase, United States
| | - Gregory Jefferis
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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18
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Nässel DR, Zandawala M. Recent advances in neuropeptide signaling in Drosophila, from genes to physiology and behavior. Prog Neurobiol 2019; 179:101607. [PMID: 30905728 DOI: 10.1016/j.pneurobio.2019.02.003] [Citation(s) in RCA: 183] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/18/2019] [Accepted: 02/28/2019] [Indexed: 12/11/2022]
Abstract
This review focuses on neuropeptides and peptide hormones, the largest and most diverse class of neuroactive substances, known in Drosophila and other animals to play roles in almost all aspects of daily life, as w;1;ell as in developmental processes. We provide an update on novel neuropeptides and receptors identified in the last decade, and highlight progress in analysis of neuropeptide signaling in Drosophila. Especially exciting is the huge amount of work published on novel functions of neuropeptides and peptide hormones in Drosophila, largely due to the rapid developments of powerful genetic methods, imaging techniques and innovative assays. We critically discuss the roles of peptides in olfaction, taste, foraging, feeding, clock function/sleep, aggression, mating/reproduction, learning and other behaviors, as well as in regulation of development, growth, metabolic and water homeostasis, stress responses, fecundity, and lifespan. We furthermore provide novel information on neuropeptide distribution and organization of peptidergic systems, as well as the phylogenetic relations between Drosophila neuropeptides and those of other phyla, including mammals. As will be shown, neuropeptide signaling is phylogenetically ancient, and not only are the structures of the peptides, precursors and receptors conserved over evolution, but also many functions of neuropeptide signaling in physiology and behavior.
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Affiliation(s)
- Dick R Nässel
- Department of Zoology, Stockholm University, Stockholm, Sweden.
| | - Meet Zandawala
- Department of Zoology, Stockholm University, Stockholm, Sweden; Department of Neuroscience, Brown University, Providence, RI, USA.
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19
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Kasture AS, Bartel D, Steinkellner T, Sucic S, Hummel T, Freissmuth M. Distinct contribution of axonal and somatodendritic serotonin transporters in drosophila olfaction. Neuropharmacology 2019; 161:107564. [PMID: 30851308 DOI: 10.1016/j.neuropharm.2019.03.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/11/2019] [Accepted: 03/03/2019] [Indexed: 01/07/2023]
Abstract
The serotonin transporter (SERT) regulates serotonergic neurotransmission by retrieving released serotonin and replenishing vesicular stores. SERT is not only delivered to axons but it is also present on the neuronal soma and on dendrites. It has not been possible to restrict the distribution of SERT without affecting transporter function. Hence, the physiological role of somatodendritic SERT remains enigmatic. The SERT C-terminus harbors a conserved RI-motif, which recruits SEC24C, a cargo receptor in the coatomer protein-II coat. Failure to engage SEC24C precludes axonal enrichment of SERT. Here we introduced a point mutation into the RI-motif of human SERT causing confinement of the resulting - otherwise fully functional - hSERT-R607A on the somatodendritic membrane of primary rat dorsal raphe neurons. Transgenic expression of the corresponding Drosophila mutant dSERT-R599A led to its enrichment in the somatodendritic compartment of serotonergic neurons in the fly brain. We explored the possible physiological role of somatodendritic SERT by comparing flies harboring wild type SERT and dSERT-R599A in a behavioral paradigm for serotonin-modulated odor perception. When globally re-expressed in serotonergic neurons, wild type SERT but not dSERT-R599A restored ethanol preference. In contrast, dSERT-R599A restored ethanol preference after targeted expression in contralaterally projecting, serotonin-immunoreactive deuterocerebral (CSD) interneurons, while expression of wild type SERT caused ethanol aversion. We conclude that, in CSD neurons, (i) somatodendritic SERT supports ethanol attraction, (ii) axonal SERT specifies ethanol aversion, (iii) the effect of axonal SERT can override that of somatodendritic SERT. These observations demonstrate a distinct biological role of somatodendritic and axonal serotonin transport. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- Ameya Sanjay Kasture
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria; Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Daniela Bartel
- Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Thomas Steinkellner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria
| | - Thomas Hummel
- Department of Neurobiology, University of Vienna, A-1090 Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, A-1090 Vienna, Austria.
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20
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Abstract
The Drosophila melanogaster larval neuromuscular system is extensively used by researchers to study neuronal cell biology, and Drosophila glutamatergic motor neurons have become a major model system. There are two main Types of glutamatergic motor neurons, Ib and Is, with different structural and physiological properties at synaptic level at the neuromuscular junction. To generate genetic tools to identify and manipulate motor neurons of each Type, we screened for GAL4 driver lines for this purpose. Here we describe GAL4 drivers specific for examples of neurons within each Type, Ib or Is. These drivers showed high expression levels and were expressed in only few motor neurons, making them amenable tools for specific studies of both axonal and synapse biology in identified Type I motor neurons.
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21
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Oswald MC, Brooks PS, Zwart MF, Mukherjee A, West RJ, Giachello CN, Morarach K, Baines RA, Sweeney ST, Landgraf M. Reactive oxygen species regulate activity-dependent neuronal plasticity in Drosophila. eLife 2018; 7:39393. [PMID: 30540251 PMCID: PMC6307858 DOI: 10.7554/elife.39393] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 12/12/2018] [Indexed: 12/11/2022] Open
Abstract
Reactive oxygen species (ROS) have been extensively studied as damaging agents associated with ageing and neurodegenerative conditions. Their role in the nervous system under non-pathological conditions has remained poorly understood. Working with the Drosophila larval locomotor network, we show that in neurons ROS act as obligate signals required for neuronal activity-dependent structural plasticity, of both pre- and postsynaptic terminals. ROS signaling is also necessary for maintaining evoked synaptic transmission at the neuromuscular junction, and for activity-regulated homeostatic adjustment of motor network output, as measured by larval crawling behavior. We identified the highly conserved Parkinson’s disease-linked protein DJ-1β as a redox sensor in neurons where it regulates structural plasticity, in part via modulation of the PTEN-PI3Kinase pathway. This study provides a new conceptual framework of neuronal ROS as second messengers required for neuronal plasticity and for network tuning, whose dysregulation in the ageing brain and under neurodegenerative conditions may contribute to synaptic dysfunction.
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Affiliation(s)
- Matthew Cw Oswald
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Paul S Brooks
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | | | - Amrita Mukherjee
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Ryan Jh West
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom.,Department of Biology, University of York, York, United Kingdom
| | - Carlo Ng Giachello
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Khomgrit Morarach
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Richard A Baines
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Sean T Sweeney
- Department of Biology, University of York, York, United Kingdom
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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22
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Zheng Z, Lauritzen JS, Perlman E, Robinson CG, Nichols M, Milkie D, Torrens O, Price J, Fisher CB, Sharifi N, Calle-Schuler SA, Kmecova L, Ali IJ, Karsh B, Trautman ET, Bogovic JA, Hanslovsky P, Jefferis GSXE, Kazhdan M, Khairy K, Saalfeld S, Fetter RD, Bock DD. A Complete Electron Microscopy Volume of the Brain of Adult Drosophila melanogaster. Cell 2018; 174:730-743.e22. [PMID: 30033368 PMCID: PMC6063995 DOI: 10.1016/j.cell.2018.06.019] [Citation(s) in RCA: 480] [Impact Index Per Article: 80.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 02/28/2018] [Accepted: 06/10/2018] [Indexed: 12/16/2022]
Abstract
Drosophila melanogaster has a rich repertoire of innate and learned behaviors. Its 100,000-neuron brain is a large but tractable target for comprehensive neural circuit mapping. Only electron microscopy (EM) enables complete, unbiased mapping of synaptic connectivity; however, the fly brain is too large for conventional EM. We developed a custom high-throughput EM platform and imaged the entire brain of an adult female fly at synaptic resolution. To validate the dataset, we traced brain-spanning circuitry involving the mushroom body (MB), which has been extensively studied for its role in learning. All inputs to Kenyon cells (KCs), the intrinsic neurons of the MB, were mapped, revealing a previously unknown cell type, postsynaptic partners of KC dendrites, and unexpected clustering of olfactory projection neurons. These reconstructions show that this freely available EM volume supports mapping of brain-spanning circuits, which will significantly accelerate Drosophila neuroscience. VIDEO ABSTRACT.
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Affiliation(s)
- Zhihao Zheng
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - J Scott Lauritzen
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Eric Perlman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Camenzind G Robinson
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Matthew Nichols
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | | | - Omar Torrens
- Coleman Technologies, Newtown Square, PA 19073, USA
| | - John Price
- Hudson Price Designs, Hingham, MA 02043, USA
| | - Corey B Fisher
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Nadiya Sharifi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | | | - Lucia Kmecova
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Iqbal J Ali
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Bill Karsh
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Eric T Trautman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - John A Bogovic
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Philipp Hanslovsky
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Gregory S X E Jefferis
- Division of Neurobiology, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Michael Kazhdan
- Department of Computer Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Khaled Khairy
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Stephan Saalfeld
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Richard D Fetter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Davi D Bock
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
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23
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Li X, Goel P, Chen C, Angajala V, Chen X, Dickman DK. Synapse-specific and compartmentalized expression of presynaptic homeostatic potentiation. eLife 2018; 7:34338. [PMID: 29620520 PMCID: PMC5927770 DOI: 10.7554/elife.34338] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 04/04/2018] [Indexed: 01/23/2023] Open
Abstract
Postsynaptic compartments can be specifically modulated during various forms of synaptic plasticity, but it is unclear whether this precision is shared at presynaptic terminals. Presynaptic homeostatic plasticity (PHP) stabilizes neurotransmission at the Drosophila neuromuscular junction, where a retrograde enhancement of presynaptic neurotransmitter release compensates for diminished postsynaptic receptor functionality. To test the specificity of PHP induction and expression, we have developed a genetic manipulation to reduce postsynaptic receptor expression at one of the two muscles innervated by a single motor neuron. We find that PHP can be induced and expressed at a subset of synapses, over both acute and chronic time scales, without influencing transmission at adjacent release sites. Further, homeostatic modulations to CaMKII, vesicle pools, and functional release sites are compartmentalized and do not spread to neighboring pre- or post-synaptic structures. Thus, both PHP induction and expression mechanisms are locally transmitted and restricted to specific synaptic compartments. Everything we think and do is the result of communication between neurons. This communication takes place at junctions called synapses. When two nerve cells or neurons communicate at a synapse, the output terminal of the first cell releases a chemical called a neurotransmitter. This binds to receiver proteins, or receptors, on the second cell. When this communication is interrupted, synapses can adapt to maintain a stable dialogue between them. This can occur in two ways. Either the first neuron starts to release more neurotransmitter from its output terminal, or the second neuron produces extra receptors with which to detect the neurotransmitter. But how specific are these changes? The brain contains far more synapses than neurons because each neuron can form synapses with many other cells. Can a neuron adjust how much of the neurotransmitter it releases at some of its synapses while leaving the others unchanged? Li et al. have now addressed this question by studying a special type of synapse that forms between neurons and muscles, known as a neuromuscular junction. At one particular neuromuscular junction in fruit flies, a single neuron splits into two output terminals, each of which forms a synapse with a different muscle. Li et al. show that when the number of neurotransmitter receptors in one of the muscles is artificially reduced, the associated output terminal compensates by increasing its neurotransmitter release. By contrast, the other output terminal remains unaffected. This suggests that a neuron can induce remarkably specific changes in a subset of its synapses. This discovery paves the way towards identifying the smallest possible unit of change that can occur in the neurons’ ability to communicate. This unit may in turn be the smallest change that can support learning. Such knowledge will help us understand how the nervous system processes and stabilizes information transfer, both in health and after injury or disease.
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Affiliation(s)
- Xiling Li
- Department of Neurobiology, University of Southern California, Los Angeles, United States.,Neuroscience Graduate Program, University of Southern California, California, United States
| | - Pragya Goel
- Department of Neurobiology, University of Southern California, Los Angeles, United States.,Graduate Program in Molecular and Computational Biology, University of Southern California, California, United States
| | - Catherine Chen
- Department of Neurobiology, University of Southern California, Los Angeles, United States
| | | | - Xun Chen
- Neuroscience Graduate Program, University of Southern California, California, United States
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24
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Nässel DR. Substrates for Neuronal Cotransmission With Neuropeptides and Small Molecule Neurotransmitters in Drosophila. Front Cell Neurosci 2018; 12:83. [PMID: 29651236 PMCID: PMC5885757 DOI: 10.3389/fncel.2018.00083] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 03/08/2018] [Indexed: 01/11/2023] Open
Abstract
It has been known for more than 40 years that individual neurons can produce more than one neurotransmitter and that neuropeptides often are colocalized with small molecule neurotransmitters (SMNs). Over the years much progress has been made in understanding the functional consequences of cotransmission in the nervous system of mammals. There are also some excellent invertebrate models that have revealed roles of coexpressed neuropeptides and SMNs in increasing complexity, flexibility, and dynamics in neuronal signaling. However, for the fly Drosophila there are surprisingly few functional studies on cotransmission, although there is ample evidence for colocalization of neuroactive compounds in neurons of the CNS, based both on traditional techniques and novel single cell transcriptome analysis. With the hope to trigger interest in initiating cotransmission studies, this review summarizes what is known about Drosophila neurons and neuronal circuits where different neuropeptides and SMNs are colocalized. Coexistence of neuroactive substances has been recorded in different neuron types such as neuroendocrine cells, interneurons, sensory cells and motor neurons. Some of the circuits highlighted here are well established in the analysis of learning and memory, circadian clock networks regulating rhythmic activity and sleep, as well as neurons and neuroendocrine cells regulating olfaction, nociception, feeding, metabolic homeostasis, diuretic functions, reproduction, and developmental processes. One emerging trait is the broad role of short neuropeptide F in cotransmission and presynaptic facilitation in a number of different neuronal circuits. This review also discusses the functional relevance of coexisting peptides in the intestine. Based on recent single cell transcriptomics data, it is likely that the neuronal systems discussed in this review are just a fraction of the total set of circuits where cotransmission occurs in Drosophila. Thus, a systematic search for colocalized neuroactive compounds in further neurons in anatomically defined circuits is of interest for the near future.
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Affiliation(s)
- Dick R Nässel
- Department of Zoology, Stockholm University, Stockholm, Sweden
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25
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Constance WD, Mukherjee A, Fisher YE, Pop S, Blanc E, Toyama Y, Williams DW. Neurexin and Neuroligin-based adhesion complexes drive axonal arborisation growth independent of synaptic activity. eLife 2018; 7:31659. [PMID: 29504935 PMCID: PMC5869020 DOI: 10.7554/elife.31659] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 03/04/2018] [Indexed: 11/25/2022] Open
Abstract
Building arborisations of the right size and shape is fundamental for neural network function. Live imaging in vertebrate brains strongly suggests that nascent synapses are critical for branch growth during development. The molecular mechanisms underlying this are largely unknown. Here we present a novel system in Drosophila for studying the development of complex arborisations live, in vivo during metamorphosis. In growing arborisations we see branch dynamics and localisations of presynaptic proteins very similar to the ‘synaptotropic growth’ described in fish/frogs. These accumulations of presynaptic proteins do not appear to be presynaptic release sites and are not paired with neurotransmitter receptors. Knockdowns of either evoked or spontaneous neurotransmission do not impact arbor growth. Instead, we find that axonal branch growth is regulated by dynamic, focal localisations of Neurexin and Neuroligin. These adhesion complexes provide stability for filopodia by a ‘stick-and-grow’ based mechanism wholly independent of synaptic activity.
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Affiliation(s)
- William D Constance
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom.,King's-NUS Joint Studentship Program, King's College London, London, United Kingdom
| | - Amrita Mukherjee
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Yvette E Fisher
- Department of Neurobiology, Stanford University, Stanford, United States.,Department of Neurobiology, Harvard Medical School, Boston, United States
| | - Sinziana Pop
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
| | - Eric Blanc
- Berlin Institute of Health, Berlin, Germany
| | - Yusuke Toyama
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore.,Temasek Life Sciences Laboratory, Singapore, Singapore.,Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Darren W Williams
- Centre for Developmental Neurobiology, King's College London, London, United Kingdom
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26
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Lizbinski KM, Dacks AM. Intrinsic and Extrinsic Neuromodulation of Olfactory Processing. Front Cell Neurosci 2018; 11:424. [PMID: 29375314 PMCID: PMC5767172 DOI: 10.3389/fncel.2017.00424] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 12/18/2017] [Indexed: 12/03/2022] Open
Abstract
Neuromodulation is a ubiquitous feature of neural systems, allowing flexible, context specific control over network dynamics. Neuromodulation was first described in invertebrate motor systems and early work established a basic dichotomy for neuromodulation as having either an intrinsic origin (i.e., neurons that participate in network coding) or an extrinsic origin (i.e., neurons from independent networks). In this conceptual dichotomy, intrinsic sources of neuromodulation provide a “memory” by adjusting network dynamics based upon previous and ongoing activation of the network itself, while extrinsic neuromodulators provide the context of ongoing activity of other neural networks. Although this dichotomy has been thoroughly considered in motor systems, it has received far less attention in sensory systems. In this review, we discuss intrinsic and extrinsic modulation in the context of olfactory processing in invertebrate and vertebrate model systems. We begin by discussing presynaptic modulation of olfactory sensory neurons by local interneurons (LNs) as a mechanism for gain control based on ongoing network activation. We then discuss the cell-class specific effects of serotonergic centrifugal neurons on olfactory processing. Finally, we briefly discuss the integration of intrinsic and extrinsic neuromodulation (metamodulation) as an effective mechanism for exerting global control over olfactory network dynamics. The heterogeneous nature of neuromodulation is a recurring theme throughout this review as the effects of both intrinsic and extrinsic modulation are generally non-uniform.
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Affiliation(s)
- Kristyn M Lizbinski
- Department of Biology, West Virginia University, Morgantown, WV, United States
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, WV, United States
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27
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Larderet I, Fritsch PM, Gendre N, Neagu-Maier GL, Fetter RD, Schneider-Mizell CM, Truman JW, Zlatic M, Cardona A, Sprecher SG. Organization of the Drosophila larval visual circuit. eLife 2017; 6:28387. [PMID: 30726702 PMCID: PMC5577918 DOI: 10.7554/elife.28387] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 08/07/2017] [Indexed: 11/20/2022] Open
Abstract
Visual systems transduce, process and transmit light-dependent environmental cues. Computation of visual features depends on photoreceptor neuron types (PR) present, organization of the eye and wiring of the underlying neural circuit. Here, we describe the circuit architecture of the visual system of Drosophila larvae by mapping the synaptic wiring diagram and neurotransmitters. By contacting different targets, the two larval PR-subtypes create two converging pathways potentially underlying the computation of ambient light intensity and temporal light changes already within this first visual processing center. Locally processed visual information then signals via dedicated projection interneurons to higher brain areas including the lateral horn and mushroom body. The stratified structure of the larval optic neuropil (LON) suggests common organizational principles with the adult fly and vertebrate visual systems. The complete synaptic wiring diagram of the LON paves the way to understanding how circuits with reduced numerical complexity control wide ranges of behaviors.
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Affiliation(s)
- Ivan Larderet
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | | | - Nanae Gendre
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | | | - Richard D Fetter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | | | - James W Truman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Marta Zlatic
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Albert Cardona
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Simon G Sprecher
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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28
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Huser A, Eschment M, Güllü N, Collins KAN, Böpple K, Pankevych L, Rolsing E, Thum AS. Anatomy and behavioral function of serotonin receptors in Drosophila melanogaster larvae. PLoS One 2017; 12:e0181865. [PMID: 28777821 PMCID: PMC5544185 DOI: 10.1371/journal.pone.0181865] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 07/07/2017] [Indexed: 12/21/2022] Open
Abstract
The biogenic amine serotonin (5-HT) is an important neuroactive molecule in the central nervous system of the majority of animal phyla. 5-HT binds to specific G protein-coupled and ligand-gated ion receptors to regulate particular aspects of animal behavior. In Drosophila, as in many other insects this includes the regulation of locomotion and feeding. Due to its genetic amenability and neuronal simplicity the Drosophila larva has turned into a useful model for studying the anatomical and molecular basis of chemosensory behaviors. This is particularly true for the olfactory system, which is mostly described down to the synaptic level over the first three orders of neuronal information processing. Here we focus on the 5-HT receptor system of the Drosophila larva. In a bipartite approach consisting of anatomical and behavioral experiments we describe the distribution and the implications of individual 5-HT receptors on naïve and acquired chemosensory behaviors. Our data suggest that 5-HT1A, 5-HT1B, and 5-HT7 are dispensable for larval naïve olfactory and gustatory choice behaviors as well as for appetitive and aversive associative olfactory learning and memory. In contrast, we show that 5-HT/5-HT2A signaling throughout development, but not as an acute neuronal function, affects associative olfactory learning and memory using high salt concentration as a negative unconditioned stimulus. These findings describe for the first time an involvement of 5-HT signaling in learning and memory in Drosophila larvae. In the longer run these results may uncover developmental, 5-HT dependent principles related to reinforcement processing possibly shared with adult Drosophila and other insects.
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Affiliation(s)
- Annina Huser
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Melanie Eschment
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Nazli Güllü
- Department of Biology, University of Konstanz, Konstanz, Germany
| | | | - Kathrin Böpple
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Lyubov Pankevych
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Emilia Rolsing
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Andreas S. Thum
- Department of Biology, University of Konstanz, Konstanz, Germany
- Zukunftskolleg, University of Konstanz, Konstanz, Germany
- Department of Genetics, University of Leipzig, Leipzig, Germany
- * E-mail:
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29
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Almeida-Carvalho MJ, Berh D, Braun A, Chen YC, Eichler K, Eschbach C, Fritsch PMJ, Gerber B, Hoyer N, Jiang X, Kleber J, Klämbt C, König C, Louis M, Michels B, Miroschnikow A, Mirth C, Miura D, Niewalda T, Otto N, Paisios E, Pankratz MJ, Petersen M, Ramsperger N, Randel N, Risse B, Saumweber T, Schlegel P, Schleyer M, Soba P, Sprecher SG, Tanimura T, Thum AS, Toshima N, Truman JW, Yarali A, Zlatic M. The Ol1mpiad: concordance of behavioural faculties of stage 1 and stage 3 Drosophila larvae. J Exp Biol 2017; 220:2452-2475. [DOI: 10.1242/jeb.156646] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 05/03/2017] [Indexed: 12/25/2022]
Abstract
ABSTRACT
Mapping brain function to brain structure is a fundamental task for neuroscience. For such an endeavour, the Drosophila larva is simple enough to be tractable, yet complex enough to be interesting. It features about 10,000 neurons and is capable of various taxes, kineses and Pavlovian conditioning. All its neurons are currently being mapped into a light-microscopical atlas, and Gal4 strains are being generated to experimentally access neurons one at a time. In addition, an electron microscopic reconstruction of its nervous system seems within reach. Notably, this electron microscope-based connectome is being drafted for a stage 1 larva – because stage 1 larvae are much smaller than stage 3 larvae. However, most behaviour analyses have been performed for stage 3 larvae because their larger size makes them easier to handle and observe. It is therefore warranted to either redo the electron microscopic reconstruction for a stage 3 larva or to survey the behavioural faculties of stage 1 larvae. We provide the latter. In a community-based approach we called the Ol1mpiad, we probed stage 1 Drosophila larvae for free locomotion, feeding, responsiveness to substrate vibration, gentle and nociceptive touch, burrowing, olfactory preference and thermotaxis, light avoidance, gustatory choice of various tastants plus odour–taste associative learning, as well as light/dark–electric shock associative learning. Quantitatively, stage 1 larvae show lower scores in most tasks, arguably because of their smaller size and lower speed. Qualitatively, however, stage 1 larvae perform strikingly similar to stage 3 larvae in almost all cases. These results bolster confidence in mapping brain structure and behaviour across developmental stages.
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Affiliation(s)
| | - Dimitri Berh
- Institute of Neurobiology and Behavioural Biology, University of Münster, 48149 Münster, Germany
- Department of Mathematics and Computer Science, University of Münster, 48149 Münster, Germany
| | - Andreas Braun
- EMBL/CRG Systems Biology Unit, Centre for Genomic Regulation, 08003 Barcelona, Spain
- Universitat Pompeu Fabra, 08002 Barcelona, Spain
| | - Yi-chun Chen
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
| | - Katharina Eichler
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Claire Eschbach
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | | | - Bertram Gerber
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
- Institute of Biology, Otto von Guericke University Magdeburg, 39118 Magdeburg, Germany
- Center for Behavioral Brain Sciences, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany
| | - Nina Hoyer
- Center for Molecular Neurobiology, University of Hamburg, 20251 Hamburg, Germany
| | - Xiaoyi Jiang
- Department of Mathematics and Computer Science, University of Münster, 48149 Münster, Germany
| | - Jörg Kleber
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
| | - Christian Klämbt
- Institute of Neurobiology and Behavioural Biology, University of Münster, 48149 Münster, Germany
| | - Christian König
- Leibniz Institute for Neurobiology (Molecular Systems Biology), 39118 Magdeburg, Germany
- Institute of Pharmacology and Toxicology, Otto von Guericke University Magdeburg, 39118 Magdeburg, Germany
| | - Matthieu Louis
- EMBL/CRG Systems Biology Unit, Centre for Genomic Regulation, 08003 Barcelona, Spain
- Universitat Pompeu Fabra, 08002 Barcelona, Spain
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93117, USA
| | - Birgit Michels
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
| | | | - Christen Mirth
- Gulbenkian Institute of Science, 2780-156 Oeiras, Portugal
- School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Daisuke Miura
- Department of Biology, Kyushu University, 819-0395 Fukuoka, Japan
| | - Thomas Niewalda
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
| | - Nils Otto
- Institute of Neurobiology and Behavioural Biology, University of Münster, 48149 Münster, Germany
| | - Emmanouil Paisios
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
| | | | - Meike Petersen
- Center for Molecular Neurobiology, University of Hamburg, 20251 Hamburg, Germany
| | - Noel Ramsperger
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - Nadine Randel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Benjamin Risse
- Institute of Neurobiology and Behavioural Biology, University of Münster, 48149 Münster, Germany
- Department of Mathematics and Computer Science, University of Münster, 48149 Münster, Germany
| | - Timo Saumweber
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
| | | | - Michael Schleyer
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
| | - Peter Soba
- Center for Molecular Neurobiology, University of Hamburg, 20251 Hamburg, Germany
| | - Simon G. Sprecher
- Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Teiichi Tanimura
- Department of Biology, Kyushu University, 819-0395 Fukuoka, Japan
| | - Andreas S. Thum
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany
| | - Naoko Toshima
- Leibniz Institute for Neurobiology (Genetics), 39118 Magdeburg, Germany
- Department of Biology, Kyushu University, 819-0395 Fukuoka, Japan
| | - Jim W. Truman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
| | - Ayse Yarali
- Center for Behavioral Brain Sciences, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany
- Leibniz Institute for Neurobiology (Molecular Systems Biology), 39118 Magdeburg, Germany
| | - Marta Zlatic
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
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30
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Identified Serotonergic Modulatory Neurons Have Heterogeneous Synaptic Connectivity within the Olfactory System of Drosophila. J Neurosci 2017; 37:7318-7331. [PMID: 28659283 DOI: 10.1523/jneurosci.0192-17.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 05/20/2017] [Accepted: 06/19/2017] [Indexed: 11/21/2022] Open
Abstract
Modulatory neurons project widely throughout the brain, dynamically altering network processing based on an animal's physiological state. The connectivity of individual modulatory neurons can be complex, as they often receive input from a variety of sources and are diverse in their physiology, structure, and gene expression profiles. To establish basic principles about the connectivity of individual modulatory neurons, we examined a pair of identified neurons, the "contralaterally projecting, serotonin-immunoreactive deutocerebral neurons" (CSDns), within the olfactory system of Drosophila Specifically, we determined the neuronal classes providing synaptic input to the CSDns within the antennal lobe (AL), an olfactory network targeted by the CSDns, and the degree to which CSDn active zones are uniformly distributed across the AL. Using anatomical techniques, we found that the CSDns received glomerulus-specific input from olfactory receptor neurons (ORNs) and projection neurons (PNs), and networkwide input from local interneurons (LNs). Furthermore, we quantified the number of CSDn active zones in each glomerulus and found that CSDn output is not uniform, but rather heterogeneous, across glomeruli and stereotyped from animal to animal. Finally, we demonstrate that the CSDns synapse broadly onto LNs and PNs throughout the AL but do not synapse upon ORNs. Our results demonstrate that modulatory neurons do not necessarily provide purely top-down input but rather receive neuron class-specific input from the networks that they target, and that even a two cell modulatory network has highly heterogeneous, yet stereotyped, pattern of connectivity.SIGNIFICANCE STATEMENT Modulatory neurons often project broadly throughout the brain to alter processing based on physiological state. However, the connectivity of individual modulatory neurons to their target networks is not well understood, as modulatory neuron populations are heterogeneous in their physiology, morphology, and gene expression. In this study, we use a pair of identified serotonergic neurons within the Drosophila olfactory system as a model to establish a framework for modulatory neuron connectivity. We demonstrate that individual modulatory neurons can integrate neuron class-specific input from their target network, which is often nonreciprocal. Additionally, modulatory neuron output can be stereotyped, yet nonuniform, across network regions. Our results provide new insight into the synaptic relationships that underlie network function of modulatory neurons.
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31
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Xu L, He J, Kaiser A, Gräber N, Schläger L, Ritze Y, Scholz H. A Single Pair of Serotonergic Neurons Counteracts Serotonergic Inhibition of Ethanol Attraction in Drosophila. PLoS One 2016; 11:e0167518. [PMID: 27936023 PMCID: PMC5147910 DOI: 10.1371/journal.pone.0167518] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 11/15/2016] [Indexed: 11/18/2022] Open
Abstract
Attraction to ethanol is common in both flies and humans, but the neuromodulatory mechanisms underlying this innate attraction are not well understood. Here, we dissect the function of the key regulator of serotonin signaling—the serotonin transporter–in innate olfactory attraction to ethanol in Drosophila melanogaster. We generated a mutated version of the serotonin transporter that prolongs serotonin signaling in the synaptic cleft and is targeted via the Gal4 system to different sets of serotonergic neurons. We identified four serotonergic neurons that inhibit the olfactory attraction to ethanol and two additional neurons that counteract this inhibition by strengthening olfactory information. Our results reveal that compensation can occur on the circuit level and that serotonin has a bidirectional function in modulating the innate attraction to ethanol. Given the evolutionarily conserved nature of the serotonin transporter and serotonin, the bidirectional serotonergic mechanisms delineate a basic principle for how random behavior is switched into targeted approach behavior.
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Affiliation(s)
- Li Xu
- Zoology, Albertus Magnus University Cologne, Köln, Germany
| | - Jianzheng He
- Zoology, Albertus Magnus University Cologne, Köln, Germany
| | - Andrea Kaiser
- Zoology, Albertus Magnus University Cologne, Köln, Germany
| | - Nikolas Gräber
- Zoology, Albertus Magnus University Cologne, Köln, Germany
| | - Laura Schläger
- Zoology, Albertus Magnus University Cologne, Köln, Germany
| | - Yvonne Ritze
- Institute of Genetics and Neurobiology, Julius Maximillian University Würzburg, Würzburg, Germany
| | - Henrike Scholz
- Zoology, Albertus Magnus University Cologne, Köln, Germany
- Institute of Genetics and Neurobiology, Julius Maximillian University Würzburg, Würzburg, Germany
- * E-mail:
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32
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Sizemore TR, Dacks AM. Serotonergic Modulation Differentially Targets Distinct Network Elements within the Antennal Lobe of Drosophila melanogaster. Sci Rep 2016; 6:37119. [PMID: 27845422 PMCID: PMC5109230 DOI: 10.1038/srep37119] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/25/2016] [Indexed: 01/10/2023] Open
Abstract
Neuromodulation confers flexibility to anatomically-restricted neural networks so that animals are able to properly respond to complex internal and external demands. However, determining the mechanisms underlying neuromodulation is challenging without knowledge of the functional class and spatial organization of neurons that express individual neuromodulatory receptors. Here, we describe the number and functional identities of neurons in the antennal lobe of Drosophila melanogaster that express each of the receptors for one such neuromodulator, serotonin (5-HT). Although 5-HT enhances odor-evoked responses of antennal lobe projection neurons (PNs) and local interneurons (LNs), the receptor basis for this enhancement is unknown. We used endogenous reporters of transcription and translation for each of the five 5-HT receptors (5-HTRs) to identify neurons, based on cell class and transmitter content, that express each receptor. We find that specific receptor types are expressed by distinct combinations of functional neuronal classes. For instance, the excitatory PNs express the excitatory 5-HTRs, while distinct classes of LNs each express different 5-HTRs. This study therefore provides a detailed atlas of 5-HT receptor expression within a well-characterized neural network, and enables future dissection of the role of serotonergic modulation of olfactory processing.
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Affiliation(s)
- Tyler R Sizemore
- Department of Biology, West Virginia University, Morgantown, WV, 26505, United States of America
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, WV, 26505, United States of America
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33
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Zhang X, Gaudry Q. Functional integration of a serotonergic neuron in the Drosophila antennal lobe. eLife 2016; 5. [PMID: 27572257 PMCID: PMC5030083 DOI: 10.7554/elife.16836] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/29/2016] [Indexed: 12/23/2022] Open
Abstract
Serotonin plays a critical role in regulating many behaviors that rely on olfaction and recently there has been great effort in determining how this molecule functions in vivo. However, it remains unknown how serotonergic neurons that innervate the first olfactory relay respond to odor stimulation and how they integrate synaptically into local circuits. We examined the sole pair of serotonergic neurons that innervates the Drosophila antennal lobe (the first olfactory relay) to characterize their physiology, connectivity, and contribution to pheromone processing. We report that nearly all odors inhibit these cells, likely through connections made reciprocally within the antennal lobe. Pharmacological and immunohistochemical analyses reveal that these neurons likely release acetylcholine in addition to serotonin and that exogenous and endogenous serotonin have opposing effects on olfactory responses. Finally, we show that activation of the entire serotonergic network, as opposed to only activation of those fibers innervating the antennal lobe, may be required for persistent serotonergic modulation of pheromone responses in the antennal lobe. DOI:http://dx.doi.org/10.7554/eLife.16836.001
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Affiliation(s)
- Xiaonan Zhang
- Department of Biology, University of Maryland, College Park, United States
| | - Quentin Gaudry
- Department of Biology, University of Maryland, College Park, United States
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34
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Berck ME, Khandelwal A, Claus L, Hernandez-Nunez L, Si G, Tabone CJ, Li F, Truman JW, Fetter RD, Louis M, Samuel AD, Cardona A. The wiring diagram of a glomerular olfactory system. eLife 2016; 5. [PMID: 27177418 PMCID: PMC4930330 DOI: 10.7554/elife.14859] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 05/06/2016] [Indexed: 12/12/2022] Open
Abstract
The sense of smell enables animals to react to long-distance cues according to learned and innate valences. Here, we have mapped with electron microscopy the complete wiring diagram of the Drosophila larval antennal lobe, an olfactory neuropil similar to the vertebrate olfactory bulb. We found a canonical circuit with uniglomerular projection neurons (uPNs) relaying gain-controlled ORN activity to the mushroom body and the lateral horn. A second, parallel circuit with multiglomerular projection neurons (mPNs) and hierarchically connected local neurons (LNs) selectively integrates multiple ORN signals already at the first synapse. LN-LN synaptic connections putatively implement a bistable gain control mechanism that either computes odor saliency through panglomerular inhibition, or allows some glomeruli to respond to faint aversive odors in the presence of strong appetitive odors. This complete wiring diagram will support experimental and theoretical studies towards bridging the gap between circuits and behavior. DOI:http://dx.doi.org/10.7554/eLife.14859.001 Our sense of smell can tell us about bread being baked faraway in the kitchen, or whether a leftover piece finally went bad. Similarly to the eyes, the nose enables us to make up a mental image of what lies at a distance. In mammals, the surface of the nose hosts a huge number of olfactory sensory cells, each of which is tuned to respond to a small set of scent molecules. The olfactory sensory cells communicate with a region of the brain called the olfactory bulb. Olfactory sensory cells of the same type converge onto the same small pocket of the olfactory bulb, forming a structure called a glomerulus. Similarly to how the retina generates an image, the combined activity of multiple glomeruli defines an odor. A particular smell is the combination of many volatile compounds, the odorants. Therefore the interactions between different olfactory glomeruli are important for defining the nature of the perceived odor. Although the types of neurons involved in these interactions were known in insects, fish and mice, a precise wiring diagram of a complete set of glomeruli had not been described. In particular, the points of contact through which neurons communicate with each other – known as synapses – among all the neurons participating in an olfactory system were not known. Berck, Khandelwal et al. have now taken advantage of the small size of the olfactory system of the larvae of Drosophila fruit flies to fully describe, using high-resolution imaging, all its neurons and their synapses. The results define the complete wiring diagram of the neural circuit that processes the signals sent by olfactory sensory neurons in the larva’s olfactory circuits. In addition to the neurons that read out the activity of a single glomerulus and send it to higher areas of the brain for further processing, there are also numerous neurons that read out activity from multiple glomeruli. These neurons represent a system, encoded in the genome, for quickly extracting valuable olfactory information and then relaying it to other areas of the brain. An essential aspect of sensation is the ability to stop noticing a stimulus if it doesn't change. This allows an animal to, for example, find food by moving in a direction that increases the intensity of an odor. Inhibition mediates some aspects of this capability. The discovery of structure in the inhibitory connections among glomeruli, together with prior findings on the inner workings of the olfactory system, enabled Berck, Khandelwal et al. to hypothesize how the olfactory circuits enable odor gradients to be navigated. Further investigation revealed more about how the circuits could detect slight changes in odor concentration regardless of whether the overall odor intensity is strong or faint. And, crucially, it revealed how the worst odors – which can signal danger – can still be perceived in the presence of very strong pleasant odors. With the wiring diagram, theories about the sense of smell can now be tested using the genetic tools available for Drosophila, leading to an understanding of how neural circuits work. DOI:http://dx.doi.org/10.7554/eLife.14859.002
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Affiliation(s)
- Matthew E Berck
- Department of Physics, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Avinash Khandelwal
- EMBL-CRG Systems Biology Program, Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Lindsey Claus
- Department of Physics, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Luis Hernandez-Nunez
- Department of Physics, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Guangwei Si
- Department of Physics, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | | | - Feng Li
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - James W Truman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Rick D Fetter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Matthieu Louis
- EMBL-CRG Systems Biology Program, Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Aravinthan Dt Samuel
- Department of Physics, Harvard University, Cambridge, United States.,Center for Brain Science, Harvard University, Cambridge, United States
| | - Albert Cardona
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
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35
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Identified Serotonin-Releasing Neurons Induce Behavioral Quiescence and Suppress Mating in Drosophila. J Neurosci 2016; 35:12792-812. [PMID: 26377467 DOI: 10.1523/jneurosci.1638-15.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Animals show different levels of activity that are reflected in sensory responsiveness and endogenously generated behaviors. Biogenic amines have been determined to be causal factors for these states of arousal. It is well established that, in Drosophila, dopamine and octopamine promote increased arousal. However, little is known about factors that regulate arousal negatively and induce states of quiescence. Moreover, it remains unclear whether global, diffuse modulatory systems comprehensively affecting brain activity determine general states of arousal. Alternatively, individual aminergic neurons might selectively modulate the animals' activity in a distinct behavioral context. Here, we show that artificially activating large populations of serotonin-releasing neurons induces behavioral quiescence and inhibits feeding and mating. We systematically narrowed down a role of serotonin in inhibiting endogenously generated locomotor activity to neurons located in the posterior medial protocerebrum. We identified neurons of this cell cluster that suppress mating, but not feeding behavior. These results suggest that serotonin does not uniformly act as global, negative modulator of general arousal. Rather, distinct serotoninergic neurons can act as inhibitory modulators of specific behaviors. SIGNIFICANCE STATEMENT An animal's responsiveness to external stimuli and its various types of endogenously generated, motivated behavior are highly dynamic and change between states of high activity and states of low activity. It remains unclear whether these states are mediated by unitary modulatory systems globally affecting brain activity, or whether distinct neurons modulate specific neuronal circuits underlying particular types of behavior. Using the model organism Drosophila melanogaster, we find that activating large proportions of serotonin-releasing neurons induces behavioral quiescence. Moreover, distinct serotonin-releasing neurons that we genetically isolated and identified negatively affect aspects of mating behavior, but not food uptake. This demonstrates that individual serotoninergic neurons can modulate distinct types of behavior selectively.
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36
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ICHINOSE T, TANIMOTO H. Dynamics of memory-guided choice behavior in Drosophila. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2016; 92:346-357. [PMID: 27725473 PMCID: PMC5243950 DOI: 10.2183/pjab.92.346] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
Memory retrieval requires both accuracy and speed. Olfactory learning of the fruit fly Drosophila melanogaster serves as a powerful model system to identify molecular and neuronal substrates of memory and memory-guided behavior. The behavioral expression of olfactory memory has traditionally been tested as a conditioned odor response in a simple T-maze, which measures the result, but not the speed, of odor choice. Here, we developed multiplexed T-mazes that allow video recording of the choice behavior. Automatic fly counting in each arm of the maze visualizes choice dynamics. Using this setup, we show that the transient blockade of serotonergic neurons slows down the choice, while leaving the eventual choice intact. In contrast, activation of the same neurons impairs the eventual performance leaving the choice speed unchanged. Our new apparatus contributes to elucidating how the speed and the accuracy of memory retrieval are implemented in the fly brain.
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Affiliation(s)
- Toshiharu ICHINOSE
- Tohoku University Graduate School of Life Sciences, Sendai, Japan
- Max-Planck Institut für Neurobiologie, Martinsried, Germany
| | - Hiromu TANIMOTO
- Tohoku University Graduate School of Life Sciences, Sendai, Japan
- Max-Planck Institut für Neurobiologie, Martinsried, Germany
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37
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Lizbinski KM, Metheny JD, Bradley SP, Kesari A, Dacks AM. The anatomical basis for modulatory convergence in the antennal lobe of Manduca sexta. J Comp Neurol 2015; 524:1859-75. [PMID: 26560074 DOI: 10.1002/cne.23926] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 11/06/2015] [Accepted: 11/09/2015] [Indexed: 12/14/2022]
Abstract
The release of neuromodulators by widely projecting neurons often allows sensory systems to alter how they process information based on the physiological state of an animal. Neuromodulators alter network function by changing the biophysical properties of individual neurons and the synaptic efficacy with which individual neurons communicate. However, most, if not all, sensory networks receive multiple neuromodulatory inputs, and the mechanisms by which sensory networks integrate multiple modulatory inputs are not well understood. Here we characterized the relative glomerular distribution of two extrinsic neuromodulators associated with distinct physiological states, serotonin (5-HT) and dopamine (DA), in the antennal lobe (AL) of the moth Manduca sexta. By using immunocytochemistry and mass dye fills, we characterized the innervation patterns of both 5-HT- and tyrosine hydroxylase-immunoreactive processes relative to each other, to olfactory receptor neurons (ORNs), to projection neurons (PNs), and to several subsets of local interneurons (LNs). 5-HT immunoreactivity had nearly complete overlap with PNs and LNs, yet no overlap with ORNs, suggesting that 5-HT may modulate PNs and LNs directly but not ORNs. TH immunoreactivity overlapped with PNs, LNs, and ORNs, suggesting that dopamine has the potential to modulate all three cell types. Furthermore, the branching density of each neuromodulator differed, with 5-HT exhibiting denser arborizations and TH-ir processes being sparser. Our results suggest that 5-HT and DA extrinsic neurons target partially overlapping glomerular regions, yet DA extends further into the region occupied by ORNs.
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Affiliation(s)
- Kristyn M Lizbinski
- Department of Biology, West Virginia University, Morgantown, West Virginia, 26505
| | - Jackie D Metheny
- Department of Biology, West Virginia University, Morgantown, West Virginia, 26505.,Center for Cardiovascular and Pulmonary Research and The Heart Center at Nationwide Children's Hospital, Columbus, Ohio, 43205
| | - Samual P Bradley
- Department of Biology, West Virginia University, Morgantown, West Virginia, 26505
| | - Aditya Kesari
- Department of Biology, West Virginia University, Morgantown, West Virginia, 26505
| | - Andrew M Dacks
- Department of Biology, West Virginia University, Morgantown, West Virginia, 26505
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38
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Ko KI, Root CM, Lindsay SA, Zaninovich OA, Shepherd AK, Wasserman SA, Kim SM, Wang JW. Starvation promotes concerted modulation of appetitive olfactory behavior via parallel neuromodulatory circuits. eLife 2015; 4:e08298. [PMID: 26208339 PMCID: PMC4531282 DOI: 10.7554/elife.08298] [Citation(s) in RCA: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 07/24/2015] [Indexed: 12/19/2022] Open
Abstract
The internal state of an organism influences its perception of attractive or aversive stimuli and thus promotes adaptive behaviors that increase its likelihood of survival. The mechanisms underlying these perceptual shifts are critical to our understanding of how neural circuits support animal cognition and behavior. Starved flies exhibit enhanced sensitivity to attractive odors and reduced sensitivity to aversive odors. Here, we show that a functional remodeling of the olfactory map is mediated by two parallel neuromodulatory systems that act in opposing directions on olfactory attraction and aversion at the level of the first synapse. Short neuropeptide F sensitizes an antennal lobe glomerulus wired for attraction, while tachykinin (DTK) suppresses activity of a glomerulus wired for aversion. Thus we show parallel neuromodulatory systems functionally reconfigure early olfactory processing to optimize detection of nutrients at the risk of ignoring potentially toxic food resources.
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Affiliation(s)
- Kang I Ko
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Cory M Root
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Scott A Lindsay
- Cell and Developmental Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Orel A Zaninovich
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Andrew K Shepherd
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Steven A Wasserman
- Cell and Developmental Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Susy M Kim
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Jing W Wang
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
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39
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Lovick JK, Hartenstein V. Hydroxyurea-mediated neuroblast ablation establishes birth dates of secondary lineages and addresses neuronal interactions in the developing Drosophila brain. Dev Biol 2015; 402:32-47. [PMID: 25773365 PMCID: PMC4472457 DOI: 10.1016/j.ydbio.2015.03.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 02/27/2015] [Accepted: 03/05/2015] [Indexed: 11/27/2022]
Abstract
The Drosophila brain is comprised of neurons formed by approximately 100 lineages, each of which is derived from a stereotyped, asymmetrically dividing neuroblast. Lineages serve as structural and developmental units of Drosophila brain anatomy and reconstruction of lineage projection patterns represents a suitable map of Drosophila brain circuitry at the level of neuron populations ("macro-circuitry"). Two phases of neuroblast proliferation, the first in the embryo and the second during the larval phase (following a period of mitotic quiescence), produce primary and secondary lineages, respectively. Using temporally controlled pulses of hydroxyurea (HU) to ablate neuroblasts and their corresponding secondary lineages during the larval phase, we analyzed the effect on development of primary and secondary lineages in the late larval and adult brain. Our findings indicate that timing of neuroblast re-activation is highly stereotyped, allowing us to establish "birth dates" for all secondary lineages. Furthermore, our results demonstrate that, whereas the trajectory and projection pattern of primary and secondary lineages is established in a largely independent manner, the final branching pattern of secondary neurons is dependent upon the presence of appropriate neuronal targets. Taken together, our data provide new insights into the degree of neuronal plasticity during Drosophila brain development.
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Affiliation(s)
- Jennifer K Lovick
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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40
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Li HH, Kroll JR, Lennox SM, Ogundeyi O, Jeter J, Depasquale G, Truman JW. A GAL4 driver resource for developmental and behavioral studies on the larval CNS of Drosophila. Cell Rep 2014; 8:897-908. [PMID: 25088417 DOI: 10.1016/j.celrep.2014.06.065] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/13/2014] [Accepted: 06/30/2014] [Indexed: 11/26/2022] Open
Abstract
We report the larval CNS expression patterns for 6,650 GAL4 lines based on cis-regulatory regions (CRMs) from the Drosophila genome. Adult CNS expression patterns were previously reported for this collection, thereby providing a unique resource for determining the origins of adult cells. An illustrative example reveals the origin of the astrocyte-like glia of the ventral CNS. Besides larval neurons and glia, the larval CNS contains scattered lineages of immature, adult-specific neurons. Comparison of lineage expression within this large collection of CRMs provides insight into the codes used for designating neuronal types. The CRMs encode both dense and sparse patterns of lineage expression. There is little correlation between brain and thoracic lineages in patterns of sparse expression, but expression in the two regions is highly correlated in the dense mode. The optic lobes, by comparison, appear to use a different set of genetic instructions in their development.
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Affiliation(s)
- Hsing-Hsi Li
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Jason R Kroll
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Sara M Lennox
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Omotara Ogundeyi
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Jennifer Jeter
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Gina Depasquale
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - James W Truman
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
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41
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Twick I, Lee JA, Ramaswami M. Olfactory habituation in Drosophila-odor encoding and its plasticity in the antennal lobe. PROGRESS IN BRAIN RESEARCH 2014; 208:3-38. [PMID: 24767477 DOI: 10.1016/b978-0-444-63350-7.00001-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
A ubiquitous feature of an animal's response to an odorant is that it declines when the odorant is frequently or continuously encountered. This decline in olfactory response, termed olfactory habituation, can have temporally or mechanistically different forms. The neural circuitry of the fruit fly Drosophila melanogaster's olfactory system is well defined in terms of component cells, which are readily accessible to functional studies and genetic manipulation. This makes it a particularly useful preparation for the investigation of olfactory habituation. In addition, the insect olfactory system shares many architectural and functional similarities with mammalian olfactory systems, suggesting that olfactory mechanisms in insects may be broadly relevant. In this chapter, we discuss the likely mechanisms of olfactory habituation in context of the participating cell types, their connectivity, and their roles in sensory processing. We overview the structure and function of key cell types, the mechanisms that stimulate them, and how they transduce and process odor signals. We then consider how each stage of olfactory processing could potentially contribute to behavioral habituation. After this, we overview a variety of recent mechanistic studies that point to an important role for potentiation of inhibitory synapses in the primary olfactory processing center, the antennal lobe, in driving the reduced response to familiar odorants. Following the discussion of mechanisms for short- and long-term olfactory habituation, we end by considering how these mechanisms may be regulated by neuromodulators, which likely play key roles in the induction, gating, or suppression of habituated behavior, and speculate on the relevance of these processes for other forms of learning and memory.
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Affiliation(s)
- Isabell Twick
- School of Genetics and Microbiology and School of Natural Sciences, Smurfit Institute of Genetics, Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland.
| | - John Anthony Lee
- School of Genetics and Microbiology and School of Natural Sciences, Smurfit Institute of Genetics, Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland.
| | - Mani Ramaswami
- School of Genetics and Microbiology and School of Natural Sciences, Smurfit Institute of Genetics, Trinity College Institute of Neuroscience, Trinity College Dublin, Ireland; National Centre for Biological Science, Bangalore, India
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42
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Dendritic growth gated by a steroid hormone receptor underlies increases in activity in the developing Drosophila locomotor system. Proc Natl Acad Sci U S A 2013; 110:E3878-87. [PMID: 24043825 DOI: 10.1073/pnas.1311711110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
As animals grow, their nervous systems also increase in size. How growth in the central nervous system is regulated and its functional consequences are incompletely understood. We explored these questions, using the larval Drosophila locomotor system as a model. In the periphery, at neuromuscular junctions, motoneurons are known to enlarge their presynaptic axon terminals in size and strength, thereby compensating for reductions in muscle excitability that are associated with increases in muscle size. Here, we studied how motoneurons change in the central nervous system during periods of animal growth. We find that within the central nervous system motoneurons also enlarge their postsynaptic dendritic arbors, by the net addition of branches, and that these scale with overall animal size. This dendritic growth is gated on a cell-by-cell basis by a specific isoform of the steroid hormone receptor ecdysone receptor-B2, for which functions have thus far remained elusive. The dendritic growth is accompanied by synaptic strengthening and results in increased neuronal activity. Electrical properties of these neurons, however, are independent of ecdysone receptor-B2 regulation. We propose that these structural dendritic changes in the central nervous system, which regulate neuronal activity, constitute an additional part of the adaptive response of the locomotor system to increases in body and muscle size as the animal grows.
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43
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Tanaka NK, Endo K, Ito K. Organization of antennal lobe-associated neurons in adult Drosophila melanogaster brain. J Comp Neurol 2013; 520:4067-130. [PMID: 22592945 DOI: 10.1002/cne.23142] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The primary olfactory centers of both vertebrates and insects are characterized by glomerular structure. Each glomerulus receives sensory input from a specific type of olfactory sensory neurons, creating a topographic map of the odor quality. The primary olfactory center is also innervated by various types of neurons such as local neurons, output projection neurons (PNs), and centrifugal neurons from higher brain regions. Although recent studies have revealed how olfactory sensory input is conveyed to each glomerulus, it still remains unclear how the information is integrated and conveyed to other brain areas. By using the GAL4 enhancer-trap system, we conducted a systematic mapping of the neurons associated with the primary olfactory center of Drosophila, the antennal lobe (AL). We identified in total 29 types of neurons, among which 13 are newly identified in the present study. Analyses of arborizations of these neurons in the AL revealed how glomeruli are linked with each other, how different PNs link these glomeruli with multiple secondary sites, and how these secondary sites are organized by the projections of the AL-associated neurons.
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Affiliation(s)
- Nobuaki K Tanaka
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo, Japan
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44
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Singh AP, Das RN, Rao G, Aggarwal A, Diegelmann S, Evers JF, Karandikar H, Landgraf M, Rodrigues V, VijayRaghavan K. Sensory neuron-derived eph regulates glomerular arbors and modulatory function of a central serotonergic neuron. PLoS Genet 2013; 9:e1003452. [PMID: 23637622 PMCID: PMC3630106 DOI: 10.1371/journal.pgen.1003452] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 02/28/2013] [Indexed: 11/30/2022] Open
Abstract
Olfactory sensory neurons connect to the antennal lobe of the fly to create the primary units for processing odor cues, the glomeruli. Unique amongst antennal-lobe neurons is an identified wide-field serotonergic neuron, the contralaterally-projecting, serotonin-immunoreactive deutocerebral neuron (CSDn). The CSDn spreads its termini all over the contralateral antennal lobe, suggesting a diffuse neuromodulatory role. A closer examination, however, reveals a restricted pattern of the CSDn arborization in some glomeruli. We show that sensory neuron-derived Eph interacts with Ephrin in the CSDn, to regulate these arborizations. Behavioural analysis of animals with altered Eph-ephrin signaling and with consequent arborization defects suggests that neuromodulation requires local glomerular-specific patterning of the CSDn termini. Our results show the importance of developmental regulation of terminal arborization of even the diffuse modulatory neurons to allow them to route sensory-inputs according to the behavioural contexts. Serotonin, a major neuromodulatory transmitter, regulates diverse behaviours. Serotonergic dysfunction is implicated in various neuropsychological disorders, such as anxiety and depression, as well as in neurodegenerative disorders. In the central nervous systems, across taxa, serotonergic neurons are often small in number but connect to and act upon multiple brain circuits through their wide-field arborization pattern. We set out to decipher mechanisms by which wide-field serotonergic neurons differentially innervate their target-field to modulate behavior in a context-dependent manner. We took advantage of the sophisticated antennal lobe circuitry, the primary olfactory centre in the adult fruitfly Drosophila melanogaster. Olfactory sensory neurons and projection neurons connect in a partner-specific manner to create glomerular units in the antennal lobe for processing the sense of smell. Our analysis at a single-cell resolution reveals that a wide-field serotonergic neuron connects to all the glomeruli in the antennal lobe but exhibits the glomerular-specific differences in its innervation pattern. Our key finding is that Eph from sensory neurons regulates the glomerular-specific innervation pattern of the central serotonergic neuron, which in turn is essential for modulation of odor-guided behaviours in an odor-specific manner.
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Affiliation(s)
- Ajeet Pratap Singh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore, India
| | - Rudra Nayan Das
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore, India
| | - Gururaj Rao
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore, India
| | - Aman Aggarwal
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore, India
| | - Soeren Diegelmann
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Jan Felix Evers
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Hrishikesh Karandikar
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Matthias Landgraf
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Veronica Rodrigues
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore, India
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - K. VijayRaghavan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore, India
- * E-mail:
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45
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Das A, Gupta T, Davla S, Godino LLP, Diegelmann S, Reddy OV, VijayRaghavan K, Reichert H, Lovick J, Hartenstein V. Neuroblast lineage-specific origin of the neurons of the Drosophila larval olfactory system. Dev Biol 2013; 373:322-37. [PMID: 23149077 PMCID: PMC4045504 DOI: 10.1016/j.ydbio.2012.11.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 11/02/2012] [Accepted: 11/06/2012] [Indexed: 11/20/2022]
Abstract
The complete neuronal repertoire of the central brain of Drosophila originates from only approximately 100 pairs of neural stem cells, or neuroblasts. Each neuroblast produces a highly stereotyped lineage of neurons which innervate specific compartments of the brain. Neuroblasts undergo two rounds of mitotic activity: embryonic divisions produce lineages of primary neurons that build the larval nervous system; after a brief quiescence, the neuroblasts go through a second round of divisions in larval stage to produce secondary neurons which are integrated into the adult nervous system. Here we investigate the lineages that are associated with the larval antennal lobe, one of the most widely studied neuronal systems in fly. We find that the same five neuroblasts responsible for the adult antennal lobe also produce the antennal lobe of the larval brain. However, there are notable differences in the composition of larval (primary) lineages and their adult (secondary) counterparts. Significantly, in the adult, two lineages (lNB/BAlc and adNB/BAmv3) produce uniglomerular projection neurons connecting the antennal lobe with the mushroom body and lateral horn; another lineage, vNB/BAla1, generates multiglomerular neurons reaching the lateral horn directly. lNB/BAlc, as well as a fourth lineage, vlNB/BAla2, generate a diversity of local interneurons. We describe a fifth, previously unknown lineage, BAlp4, which connects the posterior part of the antennal lobe and the neighboring tritocerebrum (gustatory center) with a higher brain center located adjacent to the mushroom body. In the larva, only one of these lineages, adNB/BAmv3, generates all uniglomerular projection neurons. Also as in the adult, lNB/BAlc and vlNB/BAla2 produce local interneurons which, in terms of diversity in architecture and transmitter expression, resemble their adult counterparts. In addition, lineages lNB/BAlc and vNB/BAla1, as well as the newly described BAlp4, form numerous types of projection neurons which along the same major axon pathways (antennal tracts) used by the antennal projection neurons, but which form connections that include regions outside the "classical" olfactory circuit triad antennal lobe-mushroom body-lateral horn. Our work will benefit functional studies of the larval olfactory circuit, and shed light on the relationship between larval and adult neurons.
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Affiliation(s)
- Abhijit Das
- National Centre for Biological Sciences, TIFR, UAS-GKVK Campus, Bangalore-560065, India
| | - Tripti Gupta
- National Centre for Biological Sciences, TIFR, UAS-GKVK Campus, Bangalore-560065, India
| | - Sejal Davla
- National Centre for Biological Sciences, TIFR, UAS-GKVK Campus, Bangalore-560065, India
| | | | - Sören Diegelmann
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ
| | - O. Venkateswara Reddy
- National Centre for Biological Sciences, TIFR, UAS-GKVK Campus, Bangalore-560065, India
| | - K. VijayRaghavan
- National Centre for Biological Sciences, TIFR, UAS-GKVK Campus, Bangalore-560065, India
| | - Heinrich Reichert
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
| | - Jennifer Lovick
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Volker Hartenstein
- Department of Molecular Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
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46
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The serotonergic central nervous system of the Drosophila larva: anatomy and behavioral function. PLoS One 2012; 7:e47518. [PMID: 23082175 PMCID: PMC3474743 DOI: 10.1371/journal.pone.0047518] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 09/12/2012] [Indexed: 01/03/2023] Open
Abstract
The Drosophila larva has turned into a particularly simple model system for studying the neuronal basis of innate behaviors and higher brain functions. Neuronal networks involved in olfaction, gustation, vision and learning and memory have been described during the last decade, often up to the single-cell level. Thus, most of these sensory networks are substantially defined, from the sensory level up to third-order neurons. This is especially true for the olfactory system of the larva. Given the wealth of genetic tools in Drosophila it is now possible to address the question how modulatory systems interfere with sensory systems and affect learning and memory. Here we focus on the serotonergic system that was shown to be involved in mammalian and insect sensory perception as well as learning and memory. Larval studies suggested that the serotonergic system is involved in the modulation of olfaction, feeding, vision and heart rate regulation. In a dual anatomical and behavioral approach we describe the basic anatomy of the larval serotonergic system, down to the single-cell level. In parallel, by expressing apoptosis-inducing genes during embryonic and larval development, we ablate most of the serotonergic neurons within the larval central nervous system. When testing these animals for naïve odor, sugar, salt and light perception, no profound phenotype was detectable; even appetitive and aversive learning was normal. Our results provide the first comprehensive description of the neuronal network of the larval serotonergic system. Moreover, they suggest that serotonin per se is not necessary for any of the behaviors tested. However, our data do not exclude that this system may modulate or fine-tune a wide set of behaviors, similar to its reported function in other insect species or in mammals. Based on our observations and the availability of a wide variety of genetic tools, this issue can now be addressed.
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47
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Butcher NJ, Friedrich AB, Lu Z, Tanimoto H, Meinertzhagen IA. Different classes of input and output neurons reveal new features in microglomeruli of the adult Drosophila mushroom body calyx. J Comp Neurol 2012; 520:2185-201. [DOI: 10.1002/cne.23037] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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48
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Dacks AM, Green DS, Root CM, Nighorn AJ, Wang JW. Serotonin modulates olfactory processing in the antennal lobe of Drosophila. J Neurogenet 2012; 23:366-77. [PMID: 19863268 DOI: 10.3109/01677060903085722] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Sensory systems must be able to extract features of environmental cues within the context of the different physiological states of the organism and often temper their activity in a state-dependent manner via the process of neuromodulation. We examined the effects of the neuromodulator serotonin on a well-characterized sensory circuit, the antennal lobe of Drosophila melanogaster, using two-photon microscopy and the genetically expressed calcium indicator, G-CaMP. Serotonin enhances sensitivity of the antennal lobe output projection neurons in an odor-specific manner. For odorants that sparsely activate the antennal lobe, serotonin enhances projection neuron responses and causes an offset of the projection neuron tuning curve, most likely by increasing projection neuron sensitivity. However, for an odorant that evokes a broad activation pattern, serotonin enhances projection neuron responses in some, but not all, glomeruli. Further, serotonin enhances the responses of inhibitory local interneurons, resulting in a reduction of neurotransmitter release from the olfactory sensory neurons via GABA(B) receptor-dependent presynaptic inhibition, which may be a mechanism underlying the odorant-specific modulation of projection neuron responses. Our data suggest that the complexity of serotonin modulation in the antennal lobe accommodates coding stability in a glomerular pattern and flexible projection neuron sensitivity under different physiological conditions.
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Affiliation(s)
- Andrew M Dacks
- ARL Division of Neurobiology, University of Arizona, Tucson, Arizona 85721, USA.
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49
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Abstract
Drosophila neurons have identifiable axons and dendrites based on cell shape, but it is only just starting to become clear how Drosophila neurons are polarized at the molecular level. Dendrite-specific components including the Golgi complex, GABA receptors, neurotransmitter receptor scaffolding proteins, and cell adhesion molecules have been described. Proteins involved in constructing presynaptic specializations are concentrated in axons of some neurons. A very simple model for how these components are distributed to axons and dendrites can be constructed based on the opposite polarity of microtubules in axons and dendrites: dynein carries cargo into dendrites, and kinesins carry cargo into axons. The simple model works well for multipolar neurons, but will likely need refinement for unipolar neurons, which are common in Drosophila.
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Affiliation(s)
- Melissa M Rolls
- Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
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50
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Becnel J, Johnson O, Luo J, Nässel DR, Nichols CD. The serotonin 5-HT7Dro receptor is expressed in the brain of Drosophila, and is essential for normal courtship and mating. PLoS One 2011; 6:e20800. [PMID: 21674056 PMCID: PMC3107233 DOI: 10.1371/journal.pone.0020800] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 05/12/2011] [Indexed: 12/23/2022] Open
Abstract
The 5-HT(7) receptor remains one of the less well characterized serotonin receptors. Although it has been demonstrated to be involved in the regulation of mood, sleep, and circadian rhythms, as well as relaxation of vascular smooth muscles in mammals, the precise mechanisms underlying these functions remain largely unknown. The fruit fly, Drosophila melanogaster, is an attractive model organism to study neuropharmacological, molecular, and behavioral processes that are largely conserved with mammals. Drosophila express a homolog of the mammalian 5-HT(7) receptor, as well as homologs for the mammalian 5-HT(1A), and 5-HT(2), receptors. Each fly receptor couples to the same effector pathway as their mammalian counterpart and have been demonstrated to mediate similar behavioral responses. Here, we report on the expression and function of the 5-HT(7)Dro receptor in Drosophila. In the larval central nervous system, expression is detected postsynaptically in discreet cells and neuronal circuits. In the adult brain there is strong expression in all large-field R neurons that innervate the ellipsoid body, as well as in a small group of cells that cluster with the PDF-positive LNvs neurons that mediate circadian activity. Following both pharmacological and genetic approaches, we have found that 5-HT(7)Dro activity is essential for normal courtship and mating behaviors in the fly, where it appears to mediate levels of interest in both males and females. This is the first reported evidence of direct involvement of a particular serotonin receptor subtype in courtship and mating in the fly.
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Affiliation(s)
- Jaime Becnel
- Department of Pharmacology and Experimental
Therapeutics, Louisiana State University Health Sciences Center, New Orleans,
Louisiana, United States of America
| | - Oralee Johnson
- Department of Pharmacology and Experimental
Therapeutics, Louisiana State University Health Sciences Center, New Orleans,
Louisiana, United States of America
| | - Jiangnan Luo
- Department of Zoology, Stockholm University,
Stockholm, Sweden
| | - Dick R. Nässel
- Department of Zoology, Stockholm University,
Stockholm, Sweden
| | - Charles D. Nichols
- Department of Pharmacology and Experimental
Therapeutics, Louisiana State University Health Sciences Center, New Orleans,
Louisiana, United States of America
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