{ "abstract": "The mosquito Aedes aegypti’s human host-seeking behavior depends on the integration of multiple sensory cues. One of these cues, carbon dioxide (CO2), gates odorant and heat pathways and activates host-seeking behavior. The neuronal circuits underlying processing of CO2 information remain unclear. We used automated serial-section transmission electron microscopy (EM) to image and reconstruct the circuitry of the glomeruli that are innervated by the Ae. aegypti maxillary palp, including the glomerulus that responds to CO2. Notably, CO2-sensitive olfactory sensory neurons (OSNs) make high levels of recurrent synaptic connections with one another, while making a low density of feedforward synapses. At some of these contacts between CO2 OSNs, we observe ribbon-like presynaptic structures, which may further enhance recurrent signaling. We compared both feedforward and recurrent connectivity with all olfactory glomeruli in Drosophila melanogaster, and we found more recurrent connections between the Ae. aegypti CO2-responsive OSNs than in any D. melanogaster glomeruli. We developed a computational circuit model that demonstrates recurrent synapses are necessary for robust CO2 detection under normal physiological conditions. Together, elevated levels of recurrent connectivity and ribbon-like structures may amplify sensory information detected by CO2-sensitive OSNs to support mosquito activation and sensitization by CO2, even in the presence of high levels of other odorants in the environment. We propose that this circuit organization supports the salience of CO2 as a mosquito host cue.\n\nCarbon dioxide is among the most important cues used by Aedes aegypti mosquitoes when searching for a human blood meal. This study shows that the wiring of the neurons that sense carbon dioxide differs from the wiring in Drosophila to support robust detection of this ethologically key host cue.", "abstract_shown": true, "affiliations": [ "Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America", "Molecules, Cells, and Organisms Training Program, Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, United States of America", "Department of Biology, Boston University, Boston, Massachusetts, United States of America", "Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America", "Laboratory of Neural Systems, The Rockefeller University, New York, New York, United States of America", "Department of Vision Sciences, College of Optometry, University of Houston, Houston, Texas, United States of America", "F.M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America" ], "article_type": "Research Article", "arxiv": null, "author_total": 12, "authors": [ { "affs": [ 0 ], "name": "Jialu Bao" }, { "affs": [ 1 ], "name": "Wesley Alford" }, { "affs": [ 2 ], "name": "Avinash Khandelwal" }, { "affs": [ 3 ], "name": "Laurel Walsh" }, { "affs": [ 4 ], "name": "George Lantz" }, { "affs": [ 5 ], "name": "Santiago Poncio" }, { "affs": [ 6 ], "name": "Laia Serratosa Capdevila" }, { "name": "Yervand Azatian" }, { "name": "Brian DePasquale" }, { "name": "David G. C. Hildebrand" }, { "name": "Meg A. Younger" }, { "name": "Wei-Chung Allen Lee" } ], "bibtex": "https://research.draconitic.com/paper/5wnf5z5p3dqgx.bib", "cited_by": 0, "doi": "10.1371/journal.pbio.3003959", "fulltext_url": "https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3003959", "id": "5wnf5z5p3dqgx", "issns": [ "1545-7885" ], "landing_url": "https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3003959", "language": null, "licence": "CC-BY-4.0", "licence_label": "CC BY 4.0", "licence_source": "journal", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "2804|Neurobiology and Insect Physiology Research" ], [ "plos", "/Biology and life sciences/Anatomy/Nervous system/Synapses" ], [ "plos", "/Biology and life sciences/Cell biology/Cellular structures and organelles/Vesicles" ], [ "plos", "/Biology and life sciences/Cell biology/Cellular types/Animal cells/Neurons" ], [ "plos", "/Biology and life sciences/Cell biology/Cellular types/Animal cells/Neurons/Nerve fibers/Axons" ], [ "plos", "/Biology and life sciences/Neuroscience/Cellular neuroscience/Neurons" ], [ "plos", "/Biology and life sciences/Neuroscience/Cellular neuroscience/Neurons/Nerve fibers/Axons" ], [ "plos", "/Biology and life sciences/Neuroscience/Cognitive science/Cognitive psychology/Perception/Sensory perception" ], [ "plos", "/Biology and life sciences/Neuroscience/Cognitive science/Cognitive psychology/Perception/Sensory perception/Sensory cues" ], [ "plos", "/Biology and life sciences/Neuroscience/Neurophysiology/Synapses" ], [ "plos", "/Biology and life sciences/Neuroscience/Sensory perception" ], [ "plos", "/Biology and life sciences/Neuroscience/Sensory perception/Sensory cues" ], [ "plos", "/Biology and life sciences/Organisms/Eukaryota/Animals/Invertebrates/Arthropoda/Insects/Drosophila/Drosophila melanogaster" ], [ "plos", "/Biology and life sciences/Physiology/Electrophysiology/Neurophysiology/Synapses" ], [ "plos", "/Biology and life sciences/Psychology/Cognitive psychology/Perception/Sensory perception" ], [ "plos", "/Biology and life sciences/Psychology/Cognitive psychology/Perception/Sensory perception/Sensory cues" ], [ "plos", "/Biology and life sciences/Zoology/Animals/Invertebrates/Arthropoda/Insects/Drosophila/Drosophila melanogaster" ], [ "plos", "/Biology and life sciences/Zoology/Entomology/Insects/Drosophila/Drosophila melanogaster" ], [ "plos", "/Medicine and health sciences/Anatomy/Nervous system/Synapses" ], [ "plos", "/Physical sciences/Chemistry/Chemical compounds/Carbon dioxide" ], [ "plos", "/Research and analysis methods/Animal studies/Experimental organism systems/Animal models/Drosophila melanogaster" ], [ "plos", "/Research and analysis methods/Animal studies/Experimental organism systems/Model organisms/Drosophila melanogaster" ], [ "plos", "/Research and analysis methods/Model organisms/Drosophila melanogaster" ], [ "plos", "/Social sciences/Psychology/Cognitive psychology/Perception/Sensory perception" ], [ "plos", "/Social sciences/Psychology/Cognitive psychology/Perception/Sensory perception/Sensory cues" ] ], "openalex": "W7212152300", "pdf_url": "https://journals.plos.org/plosbiology/article/file?id=10.1371/journal.pbio.3003959&type=printable", "pmcid": null, "pmid": null, "published": "2026-09-10", "publisher": "Public Library of Science", "ris": "https://research.draconitic.com/paper/5wnf5z5p3dqgx.ris", "sources": [ { "first_seen": "2026-10-30T12:17:56Z", "native_id": "10.1371/journal.pbio.3003959", "source": "plos", "url": "https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3003959" } ], "subjects": [ { "field": "biology", "origin": "plos:neuroscience", "subfield": "neuroscience" } ], "title": "Recurrent synapses between CO₂-sensitive olfactory sensory neurons enable robust CO₂ detection in Aedes aegypti mosquitoes", "title_text": "Recurrent synapses between CO₂-sensitive olfactory sensory neurons enable robust CO₂ detection in Aedes aegypti mosquitoes", "type": "peer-reviewed", "updated_at": "2026-10-30T12:17:56Z", "url": "https://research.draconitic.com/paper/5wnf5z5p3dqgx", "venue": "PLOS Biology", "versions": [] }