{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T09:19:13Z","timestamp":1783675153555,"version":"3.55.0"},"posted":{"date-parts":[[2026,7,7]]},"group-title":"Animal Behavior and Cognition","reference-count":35,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T00:00:00Z","timestamp":1783382400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"JST","award":["JPMJSP2138"],"award-info":[{"award-number":["JPMJSP2138"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,7,7]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  Animals balance staying in a favorable environment with exploring new ones. In\n                  <jats:italic>C. elegans<\/jats:italic>\n                  chemotaxis, the process by which worms migrate toward an attractant has been extensively studied. However, what happens after they reach it remains largely unexplored, partly because conventional assays immobilize worms at the point of arrival. Here, we quantitatively analyzed chemotactic behavior upon reaching an attractive odor source using an immobilization-free chemotaxis assay. We observed that 62% animals left the isoamyl alcohol region after initially approaching it, a behavior we termed \u201cleaving behavior.\u201d Quantitative analysis revealed that leaving behavior represents a distinct locomotor state compared with free-moving, high-concentration odor avoidance, and approach behavior. To test whether leaving behavior is related to olfactory adaptation, we analyzed mutants in adaptation-related genes. The proportion of leaving behavior was significantly increased in\n                  <jats:italic>egl-4<\/jats:italic>\n                  loss-of-function mutants compared with wild-type animals, whereas arr-1 mutants showed no significant difference. These results suggest that\n                  <jats:italic>egl-4<\/jats:italic>\n                  negatively regulates leaving behavior, suggesting a role for this kinase in stabilizing post-arrival behavioral states beyond its known function in olfactory adaptation. Our findings indicate that chemotaxis involves dynamic behavioral transitions even after reaching an attractant, consistent with an exploration\u2013exploitation trade-off framework.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>Significance Statement<\/jats:title>\n                  <jats:p>\n                    By eliminating immobilization from a conventional chemotaxis assay, this study reveals behaviors that are typically obscured after animals reach an attractant. In\n                    <jats:italic>C. elegans<\/jats:italic>\n                    , we identify a post-arrival behavioral mode, \u201cleaving,\u201d in which animals move away from an attractive odorant (isoamyl alcohol) after initially approaching it. Leaving behavior is quantitatively distinct from free-moving behavior, high-concentration odor avoidance, and approaching behavior. We further show that the frequency of leaving behavior is increased in animals lacking the\n                    <jats:italic>egl-4<\/jats:italic>\n                    gene. These findings extend chemotaxis analysis beyond the point of odor source arrival and suggest that the nervous system actively drives behavioral switching even after a goal is reached, broadening our understanding of how sensory circuits govern exploration\u2013exploitation decisions.\n                  <\/jats:p>\n                <\/jats:sec>","DOI":"10.64898\/2026.07.01.734387","type":"posted-content","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T22:15:17Z","timestamp":1783462517000},"source":"Crossref","is-referenced-by-count":0,"title":["Immobilization-free chemotaxis analysis reveals the novel behavioral mode of \u201cleaving\u201d in\n                  <i>Caenorhabditis elegans<\/i>"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6406-4586","authenticated-orcid":false,"given":"Shiori","family":"Onoue","sequence":"first","affiliation":[{"name":"Graduate School of Frontier Bioscience, The University of Osaka, Suita, Osaka 565-0871, Japan"},{"name":"Laboratory for Developmental Dynamics, RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9455-2153","authenticated-orcid":false,"given":"Koji","family":"Kyoda","sequence":"additional","affiliation":[{"name":"Laboratory for Developmental Dynamics, RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8255-1724","authenticated-orcid":false,"given":"Shuichi","family":"Onami","sequence":"additional","affiliation":[{"name":"Graduate School of Frontier Bioscience, The University of Osaka, Suita, Osaka 565-0871, Japan"},{"name":"Laboratory for Developmental Dynamics, RIKEN Center for Biosystems Dynamics Research, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026071002001237000_2026.07.01.734387v1.1","doi-asserted-by":"publisher","DOI":"10.1126\/science.166.3913.1588"},{"key":"2026071002001237000_2026.07.01.734387v1.2","doi-asserted-by":"publisher","DOI":"10.1523\/JNEUROSCI.1668-18.2018"},{"key":"2026071002001237000_2026.07.01.734387v1.3","doi-asserted-by":"crossref","unstructured":"Bargmann CI (2006) Chemosensation in C. elegans. WormBook. 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