1
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Faerberg DF, Aprison EZ, Ruvinsky I. Accelerated hermaphrodite maturation on male pheromones suggests a general principle of coordination between larval behavior and development. Development 2024; 151:dev202961. [PMID: 38975828 PMCID: PMC11266794 DOI: 10.1242/dev.202961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 06/04/2024] [Indexed: 07/09/2024]
Abstract
Environment in general and social signals in particular could alter development. In Caenorhabditis elegans, male pheromones hasten development of hermaphrodite larvae. We show that this involves acceleration of growth and both somatic and germline development during the last larval stage (L4). Larvae exposed to male pheromones spend more time in L3 and less in the quiescent period between L3 and L4. This behavioral alteration improves provision in early L4, likely allowing for faster development. Larvae must be exposed to male pheromones in late L3 for behavioral and developmental effects to occur. Latter portions of other larval stages also contain periods of heightened sensitivity to environmental signals. Behavior during the early part of the larval stages is biased toward exploration, whereas later the emphasis shifts to food consumption. We argue that this organization allows assessment of the environment to identify the most suitable patch of resources, followed by acquisition of sufficient nutrition and salient information for the developmental events in the next larval stage. Evidence from other species indicates that such coordination of behavior and development may be a general feature of larval development.
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Affiliation(s)
- Denis F. Faerberg
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Erin Z. Aprison
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Ilya Ruvinsky
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
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2
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Ji H, Chen D, Fang-Yen C. Segmentation-free measurement of locomotor frequency in Caenorhabditis elegans using image invariants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.16.575892. [PMID: 38293059 PMCID: PMC10827210 DOI: 10.1101/2024.01.16.575892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
An animal's locomotor rate is an important indicator of its motility. In studies of the nematode C. elegans, assays of the frequency of body bending waves have often been used to discern the effects of mutations, drugs, or aging. Traditional manual methods for measuring locomotor frequency are low in throughput and subject to human error. Most current automated methods depend on image segmentation, which requires high image quality and is prone to errors. Here, we describe an algorithm for automated estimation of C. elegans locomotor frequency using image invariants, i.e., shape-based parameters that are independent of object translation, rotation, and scaling. For each video frame, the method calculates a combination of 8 Hu's moment invariants and a set of Maximally Stable Extremal Regions (MSER) invariants. The algorithm then calculates the locomotor frequency by computing the autocorrelation of the time sequence of the invariant ensemble. Results of our method show excellent agreement with manual or segmentation-based results over a wide range of frequencies. We show that compared to a segmentation-based method that analyzes a worm's shape and a method based on video covariance, our technique is more robust to low image quality and background noise. We demonstrate the system's capabilities by testing the effects of serotonin and serotonin pathway mutations on C. elegans locomotor frequency.
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3
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Haley JA, Chalasani SH. C. elegans foraging as a model for understanding the neuronal basis of decision-making. Cell Mol Life Sci 2024; 81:252. [PMID: 38849591 PMCID: PMC11335288 DOI: 10.1007/s00018-024-05223-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/27/2024] [Accepted: 03/30/2024] [Indexed: 06/09/2024]
Abstract
Animals have evolved to seek, select, and exploit food sources in their environment. Collectively termed foraging, these ubiquitous behaviors are necessary for animal survival. As a foundation for understanding foraging, behavioral ecologists established early theoretical and mathematical frameworks which have been subsequently refined and supported by field and laboratory studies of foraging animals. These simple models sought to explain how animals decide which strategies to employ when locating food, what food items to consume, and when to explore the environment for new food sources. These foraging decisions involve integration of prior experience with multimodal sensory information about the animal's current environment and internal state. We suggest that the nematode Caenorhabditis elegans is well-suited for a high-resolution analysis of complex goal-oriented behaviors such as foraging. We focus our discussion on behavioral studies highlighting C. elegans foraging on bacteria and summarize what is known about the underlying neuronal and molecular pathways. Broadly, we suggest that this simple model system can provide a mechanistic understanding of decision-making and present additional avenues for advancing our understanding of complex behavioral processes.
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Affiliation(s)
- Jessica A Haley
- Neurosciences Graduate Program, University of California San Diego, La Jolla, CA, 92093, USA
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Sreekanth H Chalasani
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
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4
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Banse SA, Jarrett CM, Robinson KJ, Blue BW, Shaw EL, Phillips PC. The egg-counter: a novel microfluidic platform for characterization of Caenorhabditis elegans egg-laying. LAB ON A CHIP 2024; 24:2975-2986. [PMID: 38738514 PMCID: PMC11131562 DOI: 10.1039/d3lc01073b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 04/20/2024] [Indexed: 05/14/2024]
Abstract
Reproduction is a fundamental process that shapes the demography of every living organism yet is often difficult to assess with high precision in animals that produce large numbers of offspring. Here, we present a novel microfluidic research platform for studying Caenorhabditis elegans' egg-laying. The platform provides higher throughput than traditional solid-media behavioral assays while providing a very high degree of temporal resolution. Additionally, the environmental control enabled by microfluidic animal husbandry allows for experimental perturbations difficult to achieve with solid-media assays. We demonstrate the platform's utility by characterizing C. elegans egg-laying behavior at two commonly used temperatures, 15 and 20 °C. As expected, we observed a delayed onset of egg-laying at 15 °C degrees, consistent with published temperature effects on development rate. Additionally, as seen in solid media studies, egg laying output was higher under the canonical 20 °C conditions. While we validated the Egg-Counter with a study of temperature effects in wild-type animals, the platform is highly adaptable to any nematode egg-laying research where throughput or environmental control needs to be maximized without sacrificing temporal resolution.
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Affiliation(s)
- Stephen A Banse
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Cody M Jarrett
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Kristin J Robinson
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Benjamin W Blue
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Emily L Shaw
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
| | - Patrick C Phillips
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR 97403, USA.
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5
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Kann MR, Ackerman MK, Ackerman SD. OptoChamber: A Low-cost, Easy-to-Make, Customizable, and Multi-Chambered Electronic Device for Applying Optogenetic Stimulation to Larval Drosophila melanogaster. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001082. [PMID: 38681674 PMCID: PMC11056014 DOI: 10.17912/micropub.biology.001082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 03/26/2024] [Accepted: 04/11/2024] [Indexed: 05/01/2024]
Abstract
Optogenetics is a powerful tool used to manipulate physiological processes in animals through cell-specific expression of genetically modified channelrhodopsins. In Drosophila melanogaster, optogenetics is frequently used for temporal control of neuronal activation or silencing through light-dependent actuation of cation and anion channelrhodopsins, respectively. The high setup costs and complexity associated with commercially available optogenetic systems prevents many investigators from exploring the use of this technology. We developed a low-cost, customizable, and easy-to-make optogenetics chamber (OptoChamber) and verified its functionality in a robust cellular assay: activity-dependent remodeling of larval motor neurons in Drosophila embryos.
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Affiliation(s)
- Michael Ryan Kann
- Department of Pathology and Immunology, Brian Immunology & Glia (BIG) Center, Washington University in St. Louis School of Medicine, St Louis, Missouri, United States
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | | | - Sarah D. Ackerman
- Department of Pathology and Immunology, Brian Immunology & Glia (BIG) Center, Washington University in St. Louis School of Medicine, St Louis, Missouri, United States
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6
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Ji H, Chen D, Fang-Yen C. Automated multimodal imaging of Caenorhabditis elegans behavior in multi-well plates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.09.579675. [PMID: 38405855 PMCID: PMC10888940 DOI: 10.1101/2024.02.09.579675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Large-scale assays of behavior in model organisms play an important role in genetic screens, drug testing, and the elucidation of gene-behavior relationships. We have developed an automated, high-throughput imaging and analysis method for assaying behaviors of the nematode C. elegans . We use high-resolution optical imaging to longitudinally record the behaviors of 96 animals at a time in multi-well plates, and computer vision software to quantify the animals' locomotor activity, behavioral states, and egg laying events. To demonstrate the capabilities of our system we used it to examine the role of serotonin in C. elegans behavior. We found that egg-laying events are preceded by a period of reduced locomotion, and that this decline in movement requires serotonin signaling. In addition, we identified novel roles of serotonin receptors SER-1 and SER-7 in regulating the effects of serotonin on egg laying across roaming, dwelling, and quiescent locomotor states. Our system will be useful for performing genetic or chemical screens for modulators of behavior.
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McMillen A, Chew Y. Neural mechanisms of dopamine function in learning and memory in Caenorhabditis elegans. Neuronal Signal 2024; 8:NS20230057. [PMID: 38572143 PMCID: PMC10987485 DOI: 10.1042/ns20230057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 12/03/2023] [Accepted: 12/11/2023] [Indexed: 04/05/2024] Open
Abstract
Research into learning and memory over the past decades has revealed key neurotransmitters that regulate these processes, many of which are evolutionarily conserved across diverse species. The monoamine neurotransmitter dopamine is one example of this, with countless studies demonstrating its importance in regulating behavioural plasticity. However, dopaminergic neural networks in the mammalian brain consist of hundreds or thousands of neurons, and thus cannot be studied at the level of single neurons acting within defined neural circuits. The nematode Caenorhabditis elegans (C. elegans) has an experimentally tractable nervous system with a completely characterized synaptic connectome. This makes it an advantageous system to undertake mechanistic studies into how dopamine encodes lasting yet flexible behavioural plasticity in the nervous system. In this review, we synthesize the research to date exploring the importance of dopaminergic signalling in learning, memory formation, and forgetting, focusing on research in C. elegans. We also explore the potential for dopamine-specific fluorescent biosensors in C. elegans to visualize dopaminergic neural circuits during learning and memory formation in real-time. We propose that the use of these sensors in C. elegans, in combination with optogenetic and other light-based approaches, will further illuminate the detailed spatiotemporal requirements for encoding behavioural plasticity in an accessible experimental system. Understanding the key molecules and circuit mechanisms that regulate learning and forgetting in more compact invertebrate nervous systems may reveal new druggable targets for enhancing memory storage and delaying memory loss in bigger brains.
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Affiliation(s)
- Anna McMillen
- College of Medicine and Public Health and Flinders Health and Medical Research Institute, Flinders University, Bedford Park, 5042, South Australia, Australia
| | - Yee Lian Chew
- College of Medicine and Public Health and Flinders Health and Medical Research Institute, Flinders University, Bedford Park, 5042, South Australia, Australia
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8
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Abstract
Foraging animals optimize feeding decisions by adjusting both common and rare behavioral patterns. Here, we characterize the relationship between an animal's arousal state and a rare decision to leave a patch of bacterial food. Using long-term tracking and behavioral state classification, we find that food leaving decisions in Caenorhabditis elegans are coupled to arousal states across multiple timescales. Leaving emerges probabilistically over minutes from the high arousal roaming state, but is suppressed during the low arousal dwelling state. Immediately before leaving, animals have a brief acceleration in speed that appears as a characteristic signature of this behavioral motif. Neuromodulatory mutants and optogenetic manipulations that increase roaming have a coupled increase in leaving rates, and similarly acute manipulations that inhibit feeding induce both roaming and leaving. By contrast, inactivating a set of chemosensory neurons that depend on the cGMP-gated transduction channel TAX-4 uncouples roaming and leaving dynamics. In addition, tax-4-expressing sensory neurons promote lawn-leaving behaviors that are elicited by feeding inhibition. Our results indicate that sensory neurons responsive to both internal and external cues play an integrative role in arousal and foraging decisions.
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Affiliation(s)
- Elias Scheer
- Lulu and Anthony Wang Laboratory of Neural Circuits and Behavior, The Rockefeller UniversityNew YorkUnited States
| | - Cornelia I Bargmann
- Lulu and Anthony Wang Laboratory of Neural Circuits and Behavior, The Rockefeller UniversityNew YorkUnited States
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9
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Huang YC, Luo J, Huang W, Baker CM, Gomes MA, Meng B, Byrne AB, Flavell SW. A single neuron in C. elegans orchestrates multiple motor outputs through parallel modes of transmission. Curr Biol 2023; 33:4430-4445.e6. [PMID: 37769660 PMCID: PMC10860333 DOI: 10.1016/j.cub.2023.08.088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/24/2023] [Accepted: 08/30/2023] [Indexed: 10/03/2023]
Abstract
Animals generate a wide range of highly coordinated motor outputs, which allows them to execute purposeful behaviors. Individual neurons in the circuits that generate behaviors have a remarkable capacity for flexibility as they exhibit multiple axonal projections, transmitter systems, and modes of neural activity. How these multi-functional properties of neurons enable the generation of adaptive behaviors remains unknown. Here, we show that the HSN neuron in C. elegans evokes multiple motor programs over different timescales to enable a suite of behavioral changes during egg laying. Using HSN activity perturbations and in vivo calcium imaging, we show that HSN acutely increases egg laying and locomotion while also biasing the animals toward low-speed dwelling behavior over minutes. The acute effects of HSN on egg laying and high-speed locomotion are mediated by separate sets of HSN transmitters and different HSN axonal compartments. The long-lasting effects on dwelling are mediated in part by HSN release of serotonin, which is taken up and re-released by NSM, another serotonergic neuron class that directly evokes dwelling. Our results show how the multi-functional properties of a single neuron allow it to induce a coordinated suite of behaviors and also reveal that neurons can borrow serotonin from one another to control behavior.
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Affiliation(s)
- Yung-Chi Huang
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jinyue Luo
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Wenjia Huang
- Department of Neurobiology, UMass Chan Medical School, Worcester, MA 01655, USA
| | - Casey M Baker
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Matthew A Gomes
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Bohan Meng
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alexandra B Byrne
- Department of Neurobiology, UMass Chan Medical School, Worcester, MA 01655, USA
| | - Steven W Flavell
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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10
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Kochersberger A, Torkashvand MM, Lee D, Baskoylu S, Sengupta T, Koonce N, Emerson CE, Patel NV, Colón-Ramos D, Flavell S, Horvitz HR, Venkatachalam V, Hammarlund M. Programmed Cell Death Modifies Neural Circuits and Tunes Intrinsic Behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.11.557249. [PMID: 37745399 PMCID: PMC10515839 DOI: 10.1101/2023.09.11.557249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Programmed cell death is a common feature of animal development. During development of the C. elegans hermaphrodite, programmed cell death (PCD) removes 131 cells from stereotyped positions in the cell lineage, mostly in neuronal lineages. Blocking cell death results in supernumerary "undead" neurons. We find that undead neurons can be wired into circuits, can display activity, and can modify specific behaviors. The two undead RIM-like neurons participate in the RIM-containing circuit that computes movement. The addition of these two extra neurons results in animals that initiate fewer reversals and lengthens the duration of those reversals that do occur. We describe additional behavioral alterations of cell-death mutants, including in turning angle and pharyngeal pumping. These findings reveal that, like too much PCD, too little PCD can modify nervous system function and animal behavior.
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Affiliation(s)
- Alison Kochersberger
- Department of Genetics and Department of Neuroscience, Yale University School of Medicine; New Haven, CT 06536, USA
| | | | - Dongyeop Lee
- Howard Hughes Medical Institute, Department of Biology, MIT; Cambridge, MA 02139, USA
| | - Saba Baskoylu
- Picower Institute for Learning and Memory, MIT; Cambridge, MA 02139, USA
| | - Titas Sengupta
- Department of Neuroscience and Department of Cell Biology, Yale University School of Medicine; New Haven, CT 06536, USA
| | - Noelle Koonce
- Department of Neuroscience and Department of Cell Biology, Yale University School of Medicine; New Haven, CT 06536, USA
| | - Chloe E Emerson
- Department of Genetics and Department of Neuroscience, Yale University School of Medicine; New Haven, CT 06536, USA
| | - Nandan V Patel
- Department of Genetics and Department of Neuroscience, Yale University School of Medicine; New Haven, CT 06536, USA
| | - Daniel Colón-Ramos
- Department of Neuroscience and Department of Cell Biology, Yale University School of Medicine; New Haven, CT 06536, USA
- MBL Fellows, Marine Biological Laboratory; Woods Hole, MA 02543, USA
- Instituto de Neurobiología, Recinto de Ciencias Médicas, Universidad de Puerto Rico; San Juan 00901, Puerto Rico
| | - Steven Flavell
- Picower Institute for Learning and Memory, MIT; Cambridge, MA 02139, USA
| | - H Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, MIT; Cambridge, MA 02139, USA
| | | | - Marc Hammarlund
- Department of Genetics and Department of Neuroscience, Yale University School of Medicine; New Haven, CT 06536, USA
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11
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Atanas AA, Kim J, Wang Z, Bueno E, Becker M, Kang D, Park J, Kramer TS, Wan FK, Baskoylu S, Dag U, Kalogeropoulou E, Gomes MA, Estrem C, Cohen N, Mansinghka VK, Flavell SW. Brain-wide representations of behavior spanning multiple timescales and states in C. elegans. Cell 2023; 186:4134-4151.e31. [PMID: 37607537 PMCID: PMC10836760 DOI: 10.1016/j.cell.2023.07.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 07/05/2023] [Accepted: 07/28/2023] [Indexed: 08/24/2023]
Abstract
Changes in an animal's behavior and internal state are accompanied by widespread changes in activity across its brain. However, how neurons across the brain encode behavior and how this is impacted by state is poorly understood. We recorded brain-wide activity and the diverse motor programs of freely moving C. elegans and built probabilistic models that explain how each neuron encodes quantitative behavioral features. By determining the identities of the recorded neurons, we created an atlas of how the defined neuron classes in the C. elegans connectome encode behavior. Many neuron classes have conjunctive representations of multiple behaviors. Moreover, although many neurons encode current motor actions, others integrate recent actions. Changes in behavioral state are accompanied by widespread changes in how neurons encode behavior, and we identify these flexible nodes in the connectome. Our results provide a global map of how the cell types across an animal's brain encode its behavior.
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Affiliation(s)
- Adam A Atanas
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jungsoo Kim
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ziyu Wang
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Eric Bueno
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - McCoy Becker
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Di Kang
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jungyeon Park
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Talya S Kramer
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; MIT Biology Graduate Program, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Flossie K Wan
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Saba Baskoylu
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ugur Dag
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Elpiniki Kalogeropoulou
- School of Computing, University of Leeds, Leeds, UK; School of Biology, University of Leeds, Leeds, UK
| | - Matthew A Gomes
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Cassi Estrem
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Netta Cohen
- School of Computing, University of Leeds, Leeds, UK
| | - Vikash K Mansinghka
- Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Steven W Flavell
- Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
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12
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Faerberg DF, Aprison EZ, Ruvinsky I. Periods of environmental sensitivity couple larval behavior and development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.04.552015. [PMID: 37609125 PMCID: PMC10441318 DOI: 10.1101/2023.08.04.552015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The typical life cycle in most animal phyla includes a larval period that bridges embryogenesis and adulthood1. Despite the great diversity of larval forms, all larvae grow, acquire adult morphology and function, while navigating their habitats to obtain resources necessary for development. How larval development is coordinated with behavior remains substantially unclear. Here, we describe features of the iterative organization of larval stages that serve to assess the environment and procure resources prior to costly developmental commitments. We found that male-excreted pheromones accelerate2-4 the onset of adulthood in C. elegans hermaphrodites by coordinately advancing multiple developmental events and growth during the last larval stage. The larvae are sensitive to the accelerating male pheromones only at the end of the penultimate larval stage, just before the acceleration begins. Other larval stages also contain windows of sensitivity to environmental inputs. Importantly, behaviors associated with search and consumption of food are distinct between early and late portions of larval stages. We infer that each larval stage in C. elegans is subdivided into two epochs: A) global assessment of the environment to identify the most suitable patch and B) consumption of sufficient food and acquisition of salient information for developmental events in the next stage. We predict that in larvae of other species behavior is also divided into distinct epochs optimized either for assessing the habitat or obtaining the resources. Thus, a major role of larval behavior is to coordinate the orderly progression of development in variable environments.
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Affiliation(s)
- Denis F. Faerberg
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Erin Z. Aprison
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Ilya Ruvinsky
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
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13
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Cohen AE, Hastewell AD, Pradhan S, Flavell SW, Dunkel J. Schrödinger Dynamics and Berry Phase of Undulatory Locomotion. PHYSICAL REVIEW LETTERS 2023; 130:258402. [PMID: 37418715 DOI: 10.1103/physrevlett.130.258402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 05/30/2023] [Indexed: 07/09/2023]
Abstract
Spectral mode representations play an essential role in various areas of physics, from quantum mechanics to fluid turbulence, but they are not yet extensively used to characterize and describe the behavioral dynamics of living systems. Here, we show that mode-based linear models inferred from experimental live-imaging data can provide an accurate low-dimensional description of undulatory locomotion in worms, centipedes, robots, and snakes. By incorporating physical symmetries and known biological constraints into the dynamical model, we find that the shape dynamics are generically governed by Schrödinger equations in mode space. The eigenstates of the effective biophysical Hamiltonians and their adiabatic variations enable the efficient classification and differentiation of locomotion behaviors in natural, simulated, and robotic organisms using Grassmann distances and Berry phases. While our analysis focuses on a widely studied class of biophysical locomotion phenomena, the underlying approach generalizes to other physical or living systems that permit a mode representation subject to geometric shape constraints.
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Affiliation(s)
- Alexander E Cohen
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, Cambridge, Massachusetts 02142, USA
| | - Alasdair D Hastewell
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
| | - Sreeparna Pradhan
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 43 Vassar Street, Cambridge, Massachusetts 02139, USA
| | - Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 43 Vassar Street, Cambridge, Massachusetts 02139, USA
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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14
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Dag U, Nwabudike I, Kang D, Gomes MA, Kim J, Atanas AA, Bueno E, Estrem C, Pugliese S, Wang Z, Towlson E, Flavell SW. Dissecting the functional organization of the C. elegans serotonergic system at whole-brain scale. Cell 2023; 186:2574-2592.e20. [PMID: 37192620 PMCID: PMC10484565 DOI: 10.1016/j.cell.2023.04.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 03/07/2023] [Accepted: 04/17/2023] [Indexed: 05/18/2023]
Abstract
Serotonin influences many aspects of animal behavior. But how serotonin acts on its diverse receptors across the brain to modulate global activity and behavior is unknown. Here, we examine how serotonin release in C. elegans alters brain-wide activity to induce foraging behaviors, like slow locomotion and increased feeding. Comprehensive genetic analyses identify three core serotonin receptors (MOD-1, SER-4, and LGC-50) that induce slow locomotion upon serotonin release and others (SER-1, SER-5, and SER-7) that interact with them to modulate this behavior. SER-4 induces behavioral responses to sudden increases in serotonin release, whereas MOD-1 induces responses to persistent release. Whole-brain imaging reveals widespread serotonin-associated brain dynamics, spanning many behavioral networks. We map all sites of serotonin receptor expression in the connectome, which, together with synaptic connectivity, helps predict which neurons show serotonin-associated activity. These results reveal how serotonin acts at defined sites across a connectome to modulate brain-wide activity and behavior.
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Affiliation(s)
- Ugur Dag
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ijeoma Nwabudike
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Di Kang
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew A Gomes
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jungsoo Kim
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Adam A Atanas
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Computational and Systems Biology Program, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Eric Bueno
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Cassi Estrem
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sarah Pugliese
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ziyu Wang
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Emma Towlson
- Department of Computer Science, Department of Physics and Astronomy, Hotchkiss Brain Institute, Alberta Children's Research Hospital, University of Calgary, Calgary, AB, Canada
| | - Steven W Flavell
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
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15
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Thapliyal S, Beets I, Glauser DA. Multisite regulation integrates multimodal context in sensory circuits to control persistent behavioral states in C. elegans. Nat Commun 2023; 14:3052. [PMID: 37236963 DOI: 10.1038/s41467-023-38685-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
Maintaining or shifting between behavioral states according to context is essential for animals to implement fitness-promoting strategies. How the integration of internal state, past experience and sensory inputs orchestrates persistent multidimensional behavioral changes remains poorly understood. Here, we show that C. elegans integrates environmental temperature and food availability over different timescales to engage in persistent dwelling, scanning, global or glocal search strategies matching thermoregulatory and feeding needs. Transition between states, in each case, involves regulating multiple processes including AFD or FLP tonic sensory neurons activity, neuropeptide expression and downstream circuit responsiveness. State-specific FLP-6 or FLP-5 neuropeptide signaling acts on a distributed set of inhibitory GPCR(s) to promote scanning or glocal search, respectively, bypassing dopamine and glutamate-dependent behavioral state control. Integration of multimodal context via multisite regulation in sensory circuits might represent a conserved regulatory logic for a flexible prioritization on the valence of multiple inputs when operating persistent behavioral state transitions.
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Affiliation(s)
- Saurabh Thapliyal
- Department of Biology, University of Fribourg, 1700, Fribourg, Switzerland.
| | - Isabel Beets
- Neural Signaling and Circuit Plasticity Group, Department of Biology, KU Leuven, 3000, Leuven, Belgium
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16
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Ji H, Fouad AD, Li Z, Ruba A, Fang-Yen C. A proprioceptive feedback circuit drives Caenorhabditis elegans locomotor adaptation through dopamine signaling. Proc Natl Acad Sci U S A 2023; 120:e2219341120. [PMID: 37155851 PMCID: PMC10193984 DOI: 10.1073/pnas.2219341120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 04/14/2023] [Indexed: 05/10/2023] Open
Abstract
An animal adapts its motor behavior to navigate the external environment. This adaptation depends on proprioception, which provides feedback on an animal's body postures. How proprioception mechanisms interact with motor circuits and contribute to locomotor adaptation remains unclear. Here, we describe and characterize proprioception-mediated homeostatic control of undulatory movement in the roundworm Caenorhabditis elegans. We found that the worm responds to optogenetically or mechanically induced decreases in midbody bending amplitude by increasing its anterior amplitude. Conversely, it responds to increased midbody amplitude by decreasing the anterior amplitude. Using genetics, microfluidic and optogenetic perturbation response analyses, and optical neurophysiology, we elucidated the neural circuit underlying this compensatory postural response. The dopaminergic PDE neurons proprioceptively sense midbody bending and signal to AVK interneurons via the D2-like dopamine receptor DOP-3. The FMRFamide-like neuropeptide FLP-1, released by AVK, regulates SMB head motor neurons to modulate anterior bending. We propose that this homeostatic behavioral control optimizes locomotor efficiency. Our findings demonstrate a mechanism in which proprioception works with dopamine and neuropeptide signaling to mediate motor control, a motif that may be conserved in other animals.
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Affiliation(s)
- Hongfei Ji
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA19104
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH43210
| | - Anthony D. Fouad
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA19104
| | - Zihao Li
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA19104
| | - Andrew Ruba
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA19104
| | - Christopher Fang-Yen
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA19104
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH43210
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104
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17
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Huang YC, Luo J, Huang W, Baker CM, Gomes MA, Byrne AB, Flavell SW. A single neuron in C. elegans orchestrates multiple motor outputs through parallel modes of transmission. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.02.532814. [PMID: 37034579 PMCID: PMC10081309 DOI: 10.1101/2023.04.02.532814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
Animals generate a wide range of highly coordinated motor outputs, which allows them to execute purposeful behaviors. Individual neuron classes in the circuits that generate behavior have a remarkable capacity for flexibility, as they exhibit multiple axonal projections, transmitter systems, and modes of neural activity. How these multi-functional properties of neurons enable the generation of highly coordinated behaviors remains unknown. Here we show that the HSN neuron in C. elegans evokes multiple motor programs over different timescales to enable a suite of behavioral changes during egg-laying. Using HSN activity perturbations and in vivo calcium imaging, we show that HSN acutely increases egg-laying and locomotion while also biasing the animals towards low-speed dwelling behavior over longer timescales. The acute effects of HSN on egg-laying and high-speed locomotion are mediated by separate sets of HSN transmitters and different HSN axonal projections. The long-lasting effects on dwelling are mediated by HSN release of serotonin that is taken up and re-released by NSM, another serotonergic neuron class that directly evokes dwelling. Our results show how the multi-functional properties of a single neuron allow it to induce a coordinated suite of behaviors and also reveal for the first time that neurons can borrow serotonin from one another to control behavior.
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Affiliation(s)
- Yung-Chi Huang
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jinyue Luo
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Wenjia Huang
- Department of Neurobiology, UMass Chan Medical School, Worcester, MA, USA
| | - Casey M. Baker
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew A. Gomes
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Alexandra B. Byrne
- Department of Neurobiology, UMass Chan Medical School, Worcester, MA, USA
| | - Steven W. Flavell
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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18
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Sippy T, Tritsch NX. Unraveling the dynamics of dopamine release and its actions on target cells. Trends Neurosci 2023; 46:228-239. [PMID: 36635111 PMCID: PMC10204099 DOI: 10.1016/j.tins.2022.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 11/22/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023]
Abstract
The neuromodulator dopamine (DA) is essential for regulating learning, motivation, and movement. Despite its importance, however, the mechanisms by which DA influences the activity of target cells to alter behavior remain poorly understood. In this review, we describe recent methodological advances that are helping to overcome challenges that have historically hindered the field. We discuss how the employment of these methods is shedding light on the complex dynamics of extracellular DA in the brain, as well as how DA signaling alters the electrical, biochemical, and population activity of target neurons in vivo. These developments are generating novel hypotheses about the mechanisms through which DA release modifies behavior.
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Affiliation(s)
- Tanya Sippy
- Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA.
| | - Nicolas X Tritsch
- Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Fresco Institute for Parkinson's and Movement Disorders, New York University Langone Health, New York, NY, USA.
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19
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Supekar R, Song B, Hastewell A, Choi GPT, Mietke A, Dunkel J. Learning hydrodynamic equations for active matter from particle simulations and experiments. Proc Natl Acad Sci U S A 2023; 120:e2206994120. [PMID: 36763535 PMCID: PMC9963139 DOI: 10.1073/pnas.2206994120] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 01/12/2023] [Indexed: 02/11/2023] Open
Abstract
Recent advances in high-resolution imaging techniques and particle-based simulation methods have enabled the precise microscopic characterization of collective dynamics in various biological and engineered active matter systems. In parallel, data-driven algorithms for learning interpretable continuum models have shown promising potential for the recovery of underlying partial differential equations (PDEs) from continuum simulation data. By contrast, learning macroscopic hydrodynamic equations for active matter directly from experiments or particle simulations remains a major challenge, especially when continuum models are not known a priori or analytic coarse graining fails, as often is the case for nondilute and heterogeneous systems. Here, we present a framework that leverages spectral basis representations and sparse regression algorithms to discover PDE models from microscopic simulation and experimental data, while incorporating the relevant physical symmetries. We illustrate the practical potential through a range of applications, from a chiral active particle model mimicking nonidentical swimming cells to recent microroller experiments and schooling fish. In all these cases, our scheme learns hydrodynamic equations that reproduce the self-organized collective dynamics observed in the simulations and experiments. This inference framework makes it possible to measure a large number of hydrodynamic parameters in parallel and directly from video data.
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Affiliation(s)
- Rohit Supekar
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA02139
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Boya Song
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Alasdair Hastewell
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Gary P. T. Choi
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Alexander Mietke
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
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20
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Rosikon KD, Bone MC, Lawal HO. Regulation and modulation of biogenic amine neurotransmission in Drosophila and Caenorhabditis elegans. Front Physiol 2023; 14:970405. [PMID: 36875033 PMCID: PMC9978017 DOI: 10.3389/fphys.2023.970405] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 01/23/2023] [Indexed: 02/18/2023] Open
Abstract
Neurotransmitters are crucial for the relay of signals between neurons and their target. Monoamine neurotransmitters dopamine (DA), serotonin (5-HT), and histamine are found in both invertebrates and mammals and are known to control key physiological aspects in health and disease. Others, such as octopamine (OA) and tyramine (TA), are abundant in invertebrates. TA is expressed in both Caenorhabditis elegans and Drosophila melanogaster and plays important roles in the regulation of essential life functions in each organism. OA and TA are thought to act as the mammalian homologs of epinephrine and norepinephrine respectively, and when triggered, they act in response to the various stressors in the fight-or-flight response. 5-HT regulates a wide range of behaviors in C. elegans including egg-laying, male mating, locomotion, and pharyngeal pumping. 5-HT acts predominantly through its receptors, of which various classes have been described in both flies and worms. The adult brain of Drosophila is composed of approximately 80 serotonergic neurons, which are involved in modulation of circadian rhythm, feeding, aggression, and long-term memory formation. DA is a major monoamine neurotransmitter that mediates a variety of critical organismal functions and is essential for synaptic transmission in invertebrates as it is in mammals, in which it is also a precursor for the synthesis of adrenaline and noradrenaline. In C. elegans and Drosophila as in mammals, DA receptors play critical roles and are generally grouped into two classes, D1-like and D2-like based on their predicted coupling to downstream G proteins. Drosophila uses histamine as a neurotransmitter in photoreceptors as well as a small number of neurons in the CNS. C. elegans does not use histamine as a neurotransmitter. Here, we review the comprehensive set of known amine neurotransmitters found in invertebrates, and discuss their biological and modulatory functions using the vast literature on both Drosophila and C. elegans. We also suggest the potential interactions between aminergic neurotransmitters systems in the modulation of neurophysiological activity and behavior.
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Affiliation(s)
- Katarzyna D Rosikon
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Megan C Bone
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
| | - Hakeem O Lawal
- Neuroscience Program, Department of Biological Sciences, Delaware State University, Dover, DE, United States
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21
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Preusser F, Neuschulz A, Junker JP, Rajewsky N, Preibisch S. Long-term imaging reveals behavioral plasticity during C. elegans dauer exit. BMC Biol 2022; 20:277. [PMID: 36514066 DOI: 10.1186/s12915-022-01471-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/18/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND During their lifetime, animals must adapt their behavior to survive in changing environments. This ability requires the nervous system to undergo adjustments at distinct temporal scales, from short-term dynamic changes in expression of neurotransmitters and receptors to longer-term growth, spatial and connectivity reorganization, while integrating external stimuli. The nematode Caenorhabditis elegans provides a model of nervous system plasticity, in particular its dauer exit decision. Under unfavorable conditions, larvae will enter the non-feeding and non-reproductive stress-resistant dauer stage and adapt their behavior to cope with the harsh new environment, with active reversal under improved conditions leading to resumption of reproductive development. However, how different environmental stimuli regulate the exit decision mechanism and thereby drive the larva's behavioral change is unknown. To fill this gap and provide insights on behavioral changes over extended periods of time, we developed a new open hardware method for long-term imaging (12h) of C. elegans larvae. RESULTS Our WormObserver platform comprises open hardware and software components for video acquisition, automated processing of large image data (> 80k images/experiment) and data analysis. We identified dauer-specific behavioral motifs and characterized the behavioral trajectory of dauer exit in different environments and genetic backgrounds to identify key decision points and stimuli promoting dauer exit. Combining long-term behavioral imaging with transcriptomics data, we find that bacterial ingestion triggers a change in neuropeptide gene expression to establish post-dauer behavior. CONCLUSIONS Taken together, we show how a developing nervous system can robustly integrate environmental changes activate a developmental switch and adapt the organism's behavior to a new environment. WormObserver is generally applicable to other research questions within and beyond the C. elegans field, having a modular and customizable character and allowing assessment of behavioral plasticity over longer periods.
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Affiliation(s)
- Friedrich Preusser
- Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 10115, Berlin, Germany. .,Institute for Biology, Humboldt University of Berlin, 10099, Berlin, Germany.
| | - Anika Neuschulz
- Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 10115, Berlin, Germany.,Institute for Biology, Humboldt University of Berlin, 10099, Berlin, Germany
| | - Jan Philipp Junker
- Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 10115, Berlin, Germany
| | - Nikolaus Rajewsky
- Berlin Institute for Medical Systems Biology (BIMSB), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 10115, Berlin, Germany
| | - Stephan Preibisch
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, 20147, USA.
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22
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Bonnard E, Liu J, Zjacic N, Alvarez L, Scholz M. Automatically tracking feeding behavior in populations of foraging C. elegans. eLife 2022; 11:e77252. [PMID: 36083280 PMCID: PMC9462848 DOI: 10.7554/elife.77252] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 08/15/2022] [Indexed: 11/13/2022] Open
Abstract
Caenorhabditis elegans feeds on bacteria and other small microorganisms which it ingests using its pharynx, a neuromuscular pump. Currently, measuring feeding behavior requires tracking a single animal, indirectly estimating food intake from population-level metrics, or using restrained animals. To enable large throughput feeding measurements of unrestrained, crawling worms on agarose plates at a single worm resolution, we developed an imaging protocol and a complementary image analysis tool called PharaGlow. We image up to 50 unrestrained crawling worms simultaneously and extract locomotion and feeding behaviors. We demonstrate the tool's robustness and high-throughput capabilities by measuring feeding in different use-case scenarios, such as through development, with genetic and chemical perturbations that result in faster and slower pumping, and in the presence or absence of food. Finally, we demonstrate that our tool is capable of long-term imaging by showing behavioral dynamics of mating animals and worms with different genetic backgrounds. The low-resolution fluorescence microscopes required are readily available in C. elegans laboratories, and in combination with our python-based analysis workflow makes this methodology easily accessible. PharaGlow therefore enables the observation and analysis of the temporal dynamics of feeding and locomotory behaviors with high-throughput and precision in a user-friendly system.
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Affiliation(s)
- Elsa Bonnard
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Jun Liu
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Nicolina Zjacic
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
- Institute of Medical Genetics, University of ZurichZurichSwitzerland
| | - Luis Alvarez
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
| | - Monika Scholz
- Max Planck Research Group Neural Information Flow, Max Planck Institute for Neurobiology of Behavior – caesarBonnGermany
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23
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Kaźmierczak M, Nicola SM. The Arousal-motor Hypothesis of Dopamine Function: Evidence that Dopamine Facilitates Reward Seeking in Part by Maintaining Arousal. Neuroscience 2022; 499:64-103. [PMID: 35853563 PMCID: PMC9479757 DOI: 10.1016/j.neuroscience.2022.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 06/28/2022] [Accepted: 07/12/2022] [Indexed: 10/17/2022]
Abstract
Dopamine facilitates approach to reward via its actions on dopamine receptors in the nucleus accumbens. For example, blocking either D1 or D2 dopamine receptors in the accumbens reduces the proportion of reward-predictive cues to which rats respond with cued approach. Recent evidence indicates that accumbens dopamine also promotes wakefulness and arousal, but the relationship between dopamine's roles in arousal and reward seeking remains unexplored. Here, we show that the ability of systemic or intra-accumbens injections of the D1 antagonist SCH23390 to reduce cued approach to reward depends on the animal's state of arousal. Handling the animal, a manipulation known to increase arousal, was sufficient to reverse the behavioral effects of the antagonist. In addition, SCH23390 reduced spontaneous locomotion and increased time spent in sleep postures, both consistent with reduced arousal, but also increased time spent immobile in postures inconsistent with sleep. In contrast, the ability of the D2 antagonist haloperidol to reduce cued approach was not reversible by handling. Haloperidol reduced spontaneous locomotion but did not increase sleep postures, instead increasing immobility in non-sleep postures. We place these results in the context of the extensive literature on dopamine's contributions to behavior, and propose the arousal-motor hypothesis. This novel synthesis, which proposes that two main functions of dopamine are to promote arousal and facilitate motor behavior, accounts both for our findings and many previous behavioral observations that have led to disparate and conflicting conclusions.
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Affiliation(s)
- Marcin Kaźmierczak
- Departments of Neuroscience and Psychiatry, Albert Einstein College of Medicine, 1300 Morris Park Ave, Forchheimer 111, Bronx, NY 10461, USA
| | - Saleem M Nicola
- Departments of Neuroscience and Psychiatry, Albert Einstein College of Medicine, 1300 Morris Park Ave, Forchheimer 111, Bronx, NY 10461, USA.
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24
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Flavell SW, Gogolla N, Lovett-Barron M, Zelikowsky M. The emergence and influence of internal states. Neuron 2022; 110:2545-2570. [PMID: 35643077 PMCID: PMC9391310 DOI: 10.1016/j.neuron.2022.04.030] [Citation(s) in RCA: 56] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 02/11/2022] [Accepted: 04/27/2022] [Indexed: 01/09/2023]
Abstract
Animal behavior is shaped by a variety of "internal states"-partially hidden variables that profoundly shape perception, cognition, and action. The neural basis of internal states, such as fear, arousal, hunger, motivation, aggression, and many others, is a prominent focus of research efforts across animal phyla. Internal states can be inferred from changes in behavior, physiology, and neural dynamics and are characterized by properties such as pleiotropy, persistence, scalability, generalizability, and valence. To date, it remains unclear how internal states and their properties are generated by nervous systems. Here, we review recent progress, which has been driven by advances in behavioral quantification, cellular manipulations, and neural population recordings. We synthesize research implicating defined subsets of state-inducing cell types, widespread changes in neural activity, and neuromodulation in the formation and updating of internal states. In addition to highlighting the significance of these findings, our review advocates for new approaches to clarify the underpinnings of internal brain states across the animal kingdom.
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Affiliation(s)
- Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Nadine Gogolla
- Emotion Research Department, Max Planck Institute of Psychiatry, 80804 Munich, Germany; Circuits for Emotion Research Group, Max Planck Institute of Neurobiology, 82152 Martinsried, Germany.
| | - Matthew Lovett-Barron
- Division of Biological Sciences-Neurobiology Section, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Moriel Zelikowsky
- Department of Neurobiology, University of Utah, Salt Lake City, UT 84112, USA.
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25
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Mechanosensitive body–brain interactions in Caenorhabditis elegans. Curr Opin Neurobiol 2022; 75:102574. [DOI: 10.1016/j.conb.2022.102574] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 03/30/2022] [Accepted: 05/06/2022] [Indexed: 12/13/2022]
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26
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Zhang W, Zhang N, Zheng S, Zhang W, Liu J, He L, Ezemaduka AN, Li G, Ning J, Xian B, Gao S. Effects of commercial beverages on the neurobehavioral motility of Caenorhabditis elegans. PeerJ 2022; 10:e13563. [PMID: 35855427 PMCID: PMC9288823 DOI: 10.7717/peerj.13563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/19/2022] [Indexed: 01/17/2023] Open
Abstract
To study the effects of different types of commercially available drinks/beverages on neurobehavior using the model organism C. elegans, and critically review their potential health hazards. Eighteen kinds of beverages from the supermarket were randomly selected and grouped into seven categories namely functional beverage, tea beverage, plant protein beverage, fruit juice beverage, dairy beverage, carbonated beverage and coffee beverage. The pH value, specific gravity and osmotic pressure were also examined. The L4 stage N2 worms were exposed to different concentration of tested beverages (0, 62.5, 125, 250 and 500 µL/mL) for 24 h to measure the survival rate and locomotory behavior such as head thrashing, body bending as well as pharyngeal pumping. All the 18 beverages tested did not induce any visible lethal effects in the nematodes. However, exposure to different types of tested beverages exhibited different effects on the behavioral ability of C. elegans: (1) sports functional beverage and herbal tea drink accelerated the head thrashing and body bending of nematodes when compared to the control group (P < 0.05). (2) The vibration frequency of the pharyngeal pump of nematodes was significantly accelerated after treated with three plant protein beverages (almond milk, coconut milk and milk tea) and dairy products A and B (P < 0.05), and decelerated after treatment with other tested beverages. (3) Carbonated beverage significantly inhibits the head thrashing, body bending and pharyngeal pumping vibration (P < 0.05). Our results indicate that 18 kinds of popular beverages in the market have different influence on the neurobehavior in C. elegans, which may be related to their different components or properties. Further research would be required to conduct a systematic analysis of the effect of beverages by appropriate kinds, taking into consideration other endpoints such as reproduction, lifespan and molecular stress response, etc., and to elucidate the mechanism for its potential health hazards.
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Affiliation(s)
- Wenjing Zhang
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China
| | - Nan Zhang
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China
| | - Shan Zheng
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China
| | - Wei Zhang
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China
| | - Jingjing Liu
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China
| | - Liwei He
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China
| | - Anastasia Ngozi Ezemaduka
- Key Laboratory of Wetland Ecology and Environment, Northeast institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China
| | - Guojun Li
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China,School of Public Health, Capital Medical University, Beijing, China
| | - Junyu Ning
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China,School of Public Health, Capital Medical University, Beijing, China
| | - Bo Xian
- School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Shan Gao
- Beijing Center for Disease Prevention and Control, Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing, China
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27
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Serotonin and dopamine modulate aging in response to food odor and availability. Nat Commun 2022; 13:3271. [PMID: 35672307 PMCID: PMC9174215 DOI: 10.1038/s41467-022-30869-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/12/2022] [Indexed: 01/27/2023] Open
Abstract
An organism's ability to perceive and respond to changes in its environment is crucial for its health and survival. Here we reveal how the most well-studied longevity intervention, dietary restriction, acts in-part through a cell non-autonomous signaling pathway that is inhibited by the presence of attractive smells. Using an intestinal reporter for a key gene induced by dietary restriction but suppressed by attractive smells, we identify three compounds that block food odor effects in C. elegans, thereby increasing longevity as dietary restriction mimetics. These compounds clearly implicate serotonin and dopamine in limiting lifespan in response to food odor. We further identify a chemosensory neuron that likely perceives food odor, an enteric neuron that signals through the serotonin receptor 5-HT1A/SER-4, and a dopaminergic neuron that signals through the dopamine receptor DRD2/DOP-3. Aspects of this pathway are conserved in D. melanogaster. Thus, blocking food odor signaling through antagonism of serotonin or dopamine receptors is a plausible approach to mimic the benefits of dietary restriction.
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28
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Hughes S, van Dop M, Kolsters N, van de Klashorst D, Pogosova A, Rijs AM. Using a Caenorhabditis elegans Parkinson's Disease Model to Assess Disease Progression and Therapy Efficiency. Pharmaceuticals (Basel) 2022; 15:512. [PMID: 35631338 PMCID: PMC9143865 DOI: 10.3390/ph15050512] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 04/20/2022] [Accepted: 04/21/2022] [Indexed: 12/12/2022] Open
Abstract
Despite Parkinson's Disease (PD) being the second most common neurodegenerative disease, treatment options are limited. Consequently, there is an urgent need to identify and screen new therapeutic compounds that slow or reverse the pathology of PD. Unfortunately, few new therapeutics are being produced, partly due to the low throughput and/or poor predictability of the currently used model organisms and in vivo screening methods. Our objective was to develop a simple and affordable platform for drug screening utilizing the nematode Caenorhabditis elegans. The effect of Levodopa, the "Gold standard" of PD treatment, was explored in nematodes expressing the disease-causing α-synuclein protein. We focused on two key hallmarks of PD: plaque formation and mobility. Exposure to Levodopa ameliorated the mobility defect in C. elegans, similar to people living with PD who take the drug. Further, long-term Levodopa exposure was not detrimental to lifespan. This C. elegans-based method was used to screen a selection of small-molecule drugs for an impact on α-synuclein aggregation and mobility, identifying several promising compounds worthy of further investigation, most notably Ambroxol. The simple methodology means it can be adopted in many labs to pre-screen candidate compounds for a positive impact on disease progression.
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Affiliation(s)
- Samantha Hughes
- HAN BioCentre, HAN University of Applied Sciences, Laan van Scheut 2, 6525 EM Nijmegen, The Netherlands; (M.v.D.); (N.K.); (D.v.d.K.); (A.P.)
- A-LIFE Amsterdam Institute for Life and Environment, Section Environmental Health and Toxicology, Vrije Univeristeit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Maritza van Dop
- HAN BioCentre, HAN University of Applied Sciences, Laan van Scheut 2, 6525 EM Nijmegen, The Netherlands; (M.v.D.); (N.K.); (D.v.d.K.); (A.P.)
| | - Nikki Kolsters
- HAN BioCentre, HAN University of Applied Sciences, Laan van Scheut 2, 6525 EM Nijmegen, The Netherlands; (M.v.D.); (N.K.); (D.v.d.K.); (A.P.)
| | - David van de Klashorst
- HAN BioCentre, HAN University of Applied Sciences, Laan van Scheut 2, 6525 EM Nijmegen, The Netherlands; (M.v.D.); (N.K.); (D.v.d.K.); (A.P.)
| | - Anastasia Pogosova
- HAN BioCentre, HAN University of Applied Sciences, Laan van Scheut 2, 6525 EM Nijmegen, The Netherlands; (M.v.D.); (N.K.); (D.v.d.K.); (A.P.)
| | - Anouk M. Rijs
- Division of BioAnalytical Chemistry, AIMMS Amsterdam Institute of Molecular and Life Sciences, Vrije Univeristeit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
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29
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Flavell SW, Gordus A. Dynamic functional connectivity in the static connectome of Caenorhabditis elegans. Curr Opin Neurobiol 2022; 73:102515. [PMID: 35183877 PMCID: PMC9621599 DOI: 10.1016/j.conb.2021.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/16/2021] [Accepted: 12/22/2021] [Indexed: 01/01/2023]
Abstract
A hallmark of adaptive behavior is the ability to flexibly respond to sensory cues. To understand how neural circuits implement this flexibility, it is critical to resolve how a static anatomical connectome can be modulated such that functional connectivity in the network can be dynamically regulated. Here, we review recent work in the roundworm Caenorhabditis elegans on this topic. EM studies have mapped anatomical connectomes of many C. elegans animals, highlighting the level of stereotypy in the anatomical network. Brain-wide calcium imaging and studies of specified neural circuits have uncovered striking flexibility in the functional coupling of neurons. The coupling between neurons is controlled by neuromodulators that act over long timescales. This gives rise to persistent behavioral states that animals switch between, allowing them to generate adaptive behavioral responses across environmental conditions. Thus, the dynamic coupling of neurons enables multiple behavioral states to be encoded in a physically stereotyped connectome.
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Affiliation(s)
- Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Andrew Gordus
- Department of Biology, Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USA.
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30
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Jewett E, Arnott G, Connolly L, Vasudevan N, Kevei E. Microplastics and Their Impact on Reproduction-Can we Learn From the C. elegans Model? FRONTIERS IN TOXICOLOGY 2022; 4:748912. [PMID: 35399297 PMCID: PMC8987311 DOI: 10.3389/ftox.2022.748912] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 02/15/2022] [Indexed: 12/17/2022] Open
Abstract
Biologically active environmental pollutants have significant impact on ecosystems, wildlife, and human health. Microplastic (MP) and nanoplastic (NP) particles are pollutants that are present in the terrestrial and aquatic ecosystems at virtually every level of the food chain. Moreover, recently, airborne microplastic particles have been shown to reach and potentially damage respiratory systems. Microplastics and nanoplastics have been shown to cause increased oxidative stress, inflammation, altered metabolism leading to cellular damage, which ultimately affects tissue and organismal homeostasis in numerous animal species and human cells. However, the full impact of these plastic particles on living organisms is not completely understood. The ability of MPs/NPs to carry contaminants, toxic chemicals, pesticides, and bioactive compounds, such as endocrine disrupting chemicals, present an additional risk to animal and human health. This review will discusses the current knowledge on pathways by which microplastic and nanoplastic particles impact reproduction and reproductive behaviors from the level of the whole organism down to plastics-induced cellular defects, while also identifying gaps in current knowledge regarding mechanisms of action. Furthermore, we suggest that the nematode Caenorhabditis elegans provides an advantageous high-throughput model system for determining the effect of plastic particles on animal reproduction, using reproductive behavioral end points and cellular readouts.
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Affiliation(s)
- Elysia Jewett
- School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Gareth Arnott
- The Institute for Global Food Security, School of Biological Sciences, Queen’s University Belfast, Northern Ireland, United Kingdom
| | - Lisa Connolly
- The Institute for Global Food Security, School of Biological Sciences, Queen’s University Belfast, Northern Ireland, United Kingdom
| | - Nandini Vasudevan
- School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Eva Kevei
- School of Biological Sciences, University of Reading, Reading, United Kingdom
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31
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Puccetti NA, Villano WJ, Fadok JP, Heller AS. Temporal dynamics of affect in the brain: Evidence from human imaging and animal models. Neurosci Biobehav Rev 2022; 133:104491. [PMID: 34902442 PMCID: PMC8792368 DOI: 10.1016/j.neubiorev.2021.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 11/16/2021] [Accepted: 12/09/2021] [Indexed: 02/03/2023]
Abstract
Emotions are time-varying internal states that promote survival in the face of dynamic environments and shifting homeostatic needs. Research in non-human organisms has recently afforded specific insights into the neural mechanisms that support the emergence, persistence, and decay of affective states. Concurrently, a separate affective neuroscience literature has begun to dissect the neural bases of affective dynamics in humans. However, the circuit-level mechanisms identified in animals lack a clear mapping to the human neuroscience literature. As a result, critical questions pertaining to the neural bases of affective dynamics in humans remain unanswered. To address these shortcomings, the present review integrates findings from humans and non-human organisms to highlight the neural mechanisms that govern the temporal features of emotional states. Using the theory of affective chronometry as an organizing framework, we describe the specific neural mechanisms and modulatory factors that arbitrate the rise-time, intensity, and duration of emotional states.
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Affiliation(s)
- Nikki A Puccetti
- Department of Psychology, University of Miami, Coral Gables, FL, 33146, USA
| | - William J Villano
- Department of Psychology, University of Miami, Coral Gables, FL, 33146, USA
| | - Jonathan P Fadok
- Department of Psychology and Tulane Brain Institute, Tulane University, New Orleans, LA, 70118, USA
| | - Aaron S Heller
- Department of Psychology, University of Miami, Coral Gables, FL, 33146, USA.
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32
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Chou SH, Chen YJ, Liao CP, Pan CL. A role for dopamine in C. elegans avoidance behavior induced by mitochondrial stress. Neurosci Res 2022; 178:87-92. [PMID: 35074444 DOI: 10.1016/j.neures.2022.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 12/21/2021] [Accepted: 01/17/2022] [Indexed: 01/11/2023]
Abstract
Physiological stress triggers aversive learning that profoundly alters animal behavior. Systemic mitochondrial disruption induces avoidance of C. elegans to non-pathogenic food bacteria. Mutations in cat-2 and dat-1, which control dopamine synthesis and reuptake, respectively, impair this learned bacterial avoidance, suggesting that dopaminergic modulation is essential. Cell-specific rescue experiments indicate that dopamine likely acts from the CEP and ADE neurons to regulate learned bacterial avoidance. We find that mutations in multiple dopamine receptor genes, including dop-1, dop-2 and dop-3, reduced learned bacterial avoidance. Our work reveals a role for dopamine signaling in C. elegans learned avoidance behavior induced by mitochondrial stress.
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Affiliation(s)
- Shih-Hua Chou
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan; Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Yen-Ju Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan; Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Chien-Po Liao
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Chun-Liang Pan
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan; Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan.
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33
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Abstract
Studies of C. elegans behavior have been crucial in identifying genetic pathways that control nervous system development and function, as well as basic principles of neural circuit function. Modern analysis of C. elegans behavior commonly relies on video recordings of animals, followed by automated image analysis and behavior quantification. Here, we describe two methods for recording and quantifying C. elegans behavior: a single-worm tracking approach that provides high-resolution behavioral data for individual animals and a multi-worm tracking approach that allows for quantification of the behavior of many animals in parallel. These approaches should be useful to a wide range of researchers studying the nervous system and behavior of C. elegans.
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Affiliation(s)
- Navin Pokala
- Department of Biological and Chemical Sciences, Theobald Science Center, New York Institute of Technology, Old Westbury, NY, USA.
| | - Steven W Flavell
- Department of Brain & Cognitive Sciences, Picower Institute for Learning & Memory, Massachusetts Institute of Technology, Cambridge, MA, USA.
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34
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Ji N, Madan GK, Fabre GI, Dayan A, Baker CM, Kramer TS, Nwabudike I, Flavell SW. A neural circuit for flexible control of persistent behavioral states. eLife 2021; 10:e62889. [PMID: 34792019 PMCID: PMC8660023 DOI: 10.7554/elife.62889] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 11/17/2021] [Indexed: 11/29/2022] Open
Abstract
To adapt to their environments, animals must generate behaviors that are closely aligned to a rapidly changing sensory world. However, behavioral states such as foraging or courtship typically persist over long time scales to ensure proper execution. It remains unclear how neural circuits generate persistent behavioral states while maintaining the flexibility to select among alternative states when the sensory context changes. Here, we elucidate the functional architecture of a neural circuit controlling the choice between roaming and dwelling states, which underlie exploration and exploitation during foraging in C. elegans. By imaging ensemble-level neural activity in freely moving animals, we identify stereotyped changes in circuit activity corresponding to each behavioral state. Combining circuit-wide imaging with genetic analysis, we find that mutual inhibition between two antagonistic neuromodulatory systems underlies the persistence and mutual exclusivity of the neural activity patterns observed in each state. Through machine learning analysis and circuit perturbations, we identify a sensory processing neuron that can transmit information about food odors to both the roaming and dwelling circuits and bias the animal towards different states in different sensory contexts, giving rise to context-appropriate state transitions. Our findings reveal a potentially general circuit architecture that enables flexible, sensory-driven control of persistent behavioral states.
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Affiliation(s)
- Ni Ji
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Gurrein K Madan
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Guadalupe I Fabre
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Alyssa Dayan
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Casey M Baker
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Talya S Kramer
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
- MIT Biology Graduate Program, Massachusetts Institute of Technology, Cambridge, United States
| | - Ijeoma Nwabudike
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Steven W Flavell
- Picower Institute for Learning & Memory, Department of Brain & Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
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35
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Skinner DJ, Dunkel J. Estimating Entropy Production from Waiting Time Distributions. PHYSICAL REVIEW LETTERS 2021; 127:198101. [PMID: 34797138 DOI: 10.1103/physrevlett.127.198101] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 08/17/2021] [Indexed: 06/13/2023]
Abstract
Living systems operate far from thermal equilibrium by converting the chemical potential of ATP into mechanical work to achieve growth, replication, or locomotion. Given time series observations of intra-, inter-, or multicellular processes, a key challenge is to detect nonequilibrium behavior and quantify the rate of free energy consumption. Obtaining reliable bounds on energy consumption and entropy production directly from experimental data remains difficult in practice, as many degrees of freedom typically are hidden to the observer, so that the accessible coarse-grained dynamics may not obviously violate detailed balance. Here, we introduce a novel method for bounding the entropy production of physical and living systems which uses only the waiting time statistics of hidden Markov processes and, hence, can be directly applied to experimental data. By determining a universal limiting curve, we infer entropy production bounds from experimental data for gene regulatory networks, mammalian behavioral dynamics, and numerous other biological processes. Further considering the asymptotic limit of increasingly precise biological timers, we estimate the necessary entropic cost of heartbeat regulation in humans, dogs, and mice.
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Affiliation(s)
- Dominic J Skinner
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
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36
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Scharf A, Pohl F, Egan BM, Kocsisova Z, Kornfeld K. Reproductive Aging in Caenorhabditis elegans: From Molecules to Ecology. Front Cell Dev Biol 2021; 9:718522. [PMID: 34604218 PMCID: PMC8481778 DOI: 10.3389/fcell.2021.718522] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 08/04/2021] [Indexed: 11/13/2022] Open
Abstract
Aging animals display a broad range of progressive degenerative changes, and one of the most fascinating is the decline of female reproductive function. In the model organism Caenorhabditis elegans, hermaphrodites reach a peak of progeny production on day 2 of adulthood and then display a rapid decline; progeny production typically ends by day 8 of adulthood. Since animals typically survive until day 15 of adulthood, there is a substantial post reproductive lifespan. Here we review the molecular and cellular changes that occur during reproductive aging, including reductions in stem cell number and activity, slowing meiotic progression, diminished Notch signaling, and deterioration of germ line and oocyte morphology. Several interventions have been identified that delay reproductive aging, including mutations, drugs and environmental factors such as temperature. The detailed description of reproductive aging coupled with interventions that delay this process have made C. elegans a leading model system to understand the mechanisms that drive reproductive aging. While reproductive aging has dramatic consequences for individual fertility, it also has consequences for the ecology of the population. Population dynamics are driven by birth and death, and reproductive aging is one important factor that influences birth rate. A variety of theories have been advanced to explain why reproductive aging occurs and how it has been sculpted during evolution. Here we summarize these theories and discuss the utility of C. elegans for testing mechanistic and evolutionary models of reproductive aging.
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Affiliation(s)
- Andrea Scharf
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States
| | - Franziska Pohl
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Brian M Egan
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States
| | - Zuzana Kocsisova
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States
| | - Kerry Kornfeld
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States
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37
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Li H, Feng F, Zhai M, Zhang J, Jiang J, Su Y, Chen L, Gao S, Tao L, Mao H. Fast whole-body motor neuron calcium imaging of freely moving Caenorhabditis elegans without coverslip pressed. Cytometry A 2021; 99:1143-1157. [PMID: 34235849 DOI: 10.1002/cyto.a.24483] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 06/28/2021] [Accepted: 07/01/2021] [Indexed: 11/08/2022]
Abstract
Caenorhabditis elegans (C. elegans) is an ideal model organism for studying neuronal functions at the system level. This article develops a customized system for whole-body motor neuron calcium imaging of freely moving C. elegans without the coverslip pressed. Firstly, we proposed a fast centerline localization algorithm that could deal with most topology-variant cases costing only 6 ms for one frame, not only benefits for real-time localization but also for post-analysis. Secondly, we implemented a full-time two-axis synchronized motion strategy by adaptively adjusting the motion parameters of two motors in every short-term motion step (~50 ms). Following the above motion tracking configuration, the tracking performance of our system has been demonstrated to completely support the high spatiotemporal resolution calcium imaging on whole-body motor neurons of wild-type (N2) worms as well as two mutants (unc-2, unc-9), even the instantaneous speed of worm moving without coverslip pressed was extremely up to 400 μm/s.
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Affiliation(s)
- Haiwen Li
- LMAM, School of Mathematical Sciences, Peking University, Beijing, China
| | - Fan Feng
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China
| | - Muyue Zhai
- Institute of Molecular Medicine, Peking University, Beijing, China
| | - Jiazhi Zhang
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China
| | - Jingyuan Jiang
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China
| | - Yifan Su
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China
| | - Liangyi Chen
- Institute of Molecular Medicine, Peking University, Beijing, China
| | - Shangbang Gao
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Louis Tao
- Center for Bioinformatics, National Laboratory of Protein Engineering and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China.,Center for Quantitative Biology, Peking University, Beijing, China
| | - Heng Mao
- LMAM, School of Mathematical Sciences, Peking University, Beijing, China.,Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing, China
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38
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Backes C, Martinez-Martinez D, Cabreiro F. C. elegans: A biosensor for host-microbe interactions. Lab Anim (NY) 2021; 50:127-135. [PMID: 33649581 DOI: 10.1038/s41684-021-00724-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/27/2021] [Indexed: 01/31/2023]
Abstract
Microbes are an integral part of life on this planet. Microbes and their hosts influence each other in an endless dance that shapes how the meta-organism interacts with its environment. Although great advances have been made in microbiome research over the past 20 years, the mechanisms by which both hosts and their microbes interact with each other and the environment are still not well understood. The nematode Caenorhabditis elegans has been widely used as a model organism to study a remarkable number of human-like processes. Recent evidence shows that the worm is a powerful tool to investigate in fine detail the complexity that exists in microbe-host interactions. By combining the large array of genetic tools available for both organisms together with deep phenotyping approaches, it has been possible to uncover key effectors in the complex relationship between microbes and their hosts. In this perspective, we survey the literature for insightful discoveries in the microbiome field using the worm as a model. We discuss the latest conceptual and technological advances in the field and highlight the strengths that make C. elegans a valuable biosensor tool for the study of microbe-host interactions.
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Affiliation(s)
- Cassandra Backes
- MRC London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK
| | | | - Filipe Cabreiro
- MRC London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK. .,Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK.
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39
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Xu Y, Zhang L, Liu Y, Topalidou I, Hassinan C, Ailion M, Zhao Z, Wang T, Chen Z, Bai J. Dopamine receptor DOP-1 engages a sleep pathway to modulate swimming in C. elegans. iScience 2021; 24:102247. [PMID: 33796839 PMCID: PMC7995527 DOI: 10.1016/j.isci.2021.102247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 02/06/2021] [Accepted: 02/25/2021] [Indexed: 12/26/2022] Open
Abstract
Animals require robust yet flexible programs to support locomotion. Here we report a pathway that connects the D1-like dopamine receptor DOP-1 with a sleep mechanism to modulate swimming in C. elegans. We show that DOP-1 plays a negative role in sustaining swimming behavior. By contrast, a pathway through the D2-like dopamine receptor DOP-3 negatively regulates the initiation of swimming, but its impact fades quickly over a few minutes. We find that DOP-1 and the GPCR kinase (G-protein-coupled receptor kinase-2) function in the sleep interneuron RIS, where DOP-1 modulates the secretion of a sleep neuropeptide FLP-11. We further show that DOP-1 and FLP-11 act in the same pathway to modulate swimming. Together, these results delineate a functional connection between a dopamine receptor and a sleep program to regulate swimming in C. elegans. The temporal transition between DOP-3 and DOP-1 pathways highlights the dynamic nature of neuromodulation for rhythmic movements that persist over time.
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Affiliation(s)
- Ye Xu
- Department of Clinical Medicine, Nanjing Medical University, Nanjing 211166, P. R. China.,Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA.,Department of Neurology, First Affiliated Hospital of Hainan Medical University, Hainan Medical University, Hainan 570102, P. R. China
| | - Lin Zhang
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA
| | - Yan Liu
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA
| | - Irini Topalidou
- Department of Biochemistry, University of Washington, WA 98195
| | - Cera Hassinan
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98019
| | - Michael Ailion
- Department of Biochemistry, University of Washington, WA 98195
| | - Zhenqiang Zhao
- Department of Neurology, First Affiliated Hospital of Hainan Medical University, Hainan Medical University, Hainan 570102, P. R. China
| | - Tan Wang
- Department of Neurology, First Affiliated Hospital of Hainan Medical University, Hainan Medical University, Hainan 570102, P. R. China
| | - Zhibin Chen
- Department of Clinical Medicine, Nanjing Medical University, Nanjing 211166, P. R. China.,Department of Neurology, First Affiliated Hospital of Hainan Medical University, Hainan Medical University, Hainan 570102, P. R. China
| | - Jihong Bai
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA.,Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98019.,Department of Biochemistry, University of Washington, WA 98195
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Abstract
Caenorhabditis elegans' behavioral states, like those of other animals, are shaped by its immediate environment, its past experiences, and by internal factors. We here review the literature on C. elegans behavioral states and their regulation. We discuss dwelling and roaming, local and global search, mate finding, sleep, and the interaction between internal metabolic states and behavior.
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Affiliation(s)
- Steven W Flavell
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - David M Raizen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Young-Jai You
- Division of Biological Science, Graduate School of Science, Nagoya University, 464-8602, Japan
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Alcedo J, Prahlad V. Neuromodulators: an essential part of survival. J Neurogenet 2020; 34:475-481. [PMID: 33170042 PMCID: PMC7811185 DOI: 10.1080/01677063.2020.1839066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/15/2020] [Indexed: 10/23/2022]
Abstract
The coordination between the animal's external environment and internal state requires constant modulation by chemicals known as neuromodulators. Neuromodulators, such as biogenic amines, neuropeptides and cytokines, promote organismal homeostasis. Over the past several decades, Caenorhabditiselegans has grown into a powerful model organism that allows the elucidation of the mechanisms of action of neuromodulators that are conserved across species. In this perspective, we highlight a collection of articles in this issue that describe how neuromodulators optimize C. elegans survival.
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Affiliation(s)
- Joy Alcedo
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Veena Prahlad
- Department of Biology, Aging Mind and Brain Initiative, and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
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Cellular Expression and Functional Roles of All 26 Neurotransmitter GPCRs in the C. elegans Egg-Laying Circuit. J Neurosci 2020; 40:7475-7488. [PMID: 32847964 DOI: 10.1523/jneurosci.1357-20.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/28/2020] [Accepted: 08/13/2020] [Indexed: 01/06/2023] Open
Abstract
Maps of the synapses made and neurotransmitters released by all neurons in model systems, such as Caenorhabditis elegans have left still unresolved how neural circuits integrate and respond to neurotransmitter signals. Using the egg-laying circuit of C. elegans as a model, we mapped which cells express each of the 26 neurotransmitter GPCRs of this organism and also genetically analyzed the functions of all 26 GPCRs. We found that individual neurons express many distinct receptors, epithelial cells often express neurotransmitter receptors, and receptors are often positioned to receive extrasynaptic signals. Receptor knockouts reveal few egg-laying defects under standard laboratory conditions, suggesting that the receptors function redundantly or regulate egg-laying only in specific conditions; however, increasing receptor signaling through overexpression more efficiently reveals receptor functions. This map of neurotransmitter GPCR expression and function in the egg-laying circuit provides a model for understanding GPCR signaling in other neural circuits.SIGNIFICANCE STATEMENT Neurotransmitters signal through GPCRs to modulate activity of neurons, and changes in such signaling can underlie conditions such as depression and Parkinson's disease. To determine how neurotransmitter GPCRs together help regulate function of a neural circuit, we analyzed the simple egg-laying circuit in the model organism C. elegans We identified all the cells that express every neurotransmitter GPCR and genetically analyzed how each GPCR affects the behavior the circuit produces. We found that many neurotransmitter GPCRs are expressed in each neuron, that neurons also appear to use these receptors to communicate with other cell types, and that GPCRs appear to often act redundantly or only under specific conditions to regulate circuit function.
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Abstract
Microbes are ubiquitous in the natural environment of Caenorhabditis elegans. Bacteria serve as a food source for C. elegans but may also cause infection in the nematode host. The sensory nervous system of C. elegans detects diverse microbial molecules, ranging from metabolites produced by broad classes of bacteria to molecules synthesized by specific strains of bacteria. Innate recognition through chemosensation of bacterial metabolites or mechanosensation of bacteria can induce immediate behavioral responses. The ingestion of nutritive or pathogenic bacteria can modulate internal states that underlie long-lasting behavioral changes. Ingestion of nutritive bacteria leads to learned attraction and exploitation of the bacterial food source. Infection, which is accompanied by activation of innate immunity, stress responses, and host damage, leads to the development of aversive behavior. The integration of a multitude of microbial sensory cues in the environment is shaped by experience and context. Genetic, chemical, and neuronal studies of C. elegans behavior in the presence of bacteria have defined neural circuits and neuromodulatory systems that shape innate and learned behavioral responses to microbial cues. These studies have revealed the profound influence that host-microbe interactions have in governing the behavior of this simple animal host.
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Affiliation(s)
- Dennis H Kim
- Division of Infectious Diseases, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Steven W Flavell
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
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