{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,2]],"date-time":"2026-09-02T13:20:37Z","timestamp":1788355237594,"version":"build-2803163510"},"reference-count":12,"publisher":"AIP Publishing","issue":"9","funder":[{"DOI":"10.13039\/501100004564","name":"Ministarstvo Prosvete, Nauke i Tehnolo\u0161kog Razvoja","doi-asserted-by":"publisher","award":["Contract No. 451-03-33\/2026-03\/200017"],"award-info":[{"award-number":["Contract No. 451-03-33\/2026-03\/200017"]}],"id":[{"id":"10.13039\/501100004564","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000006","name":"Office of Naval Research","doi-asserted-by":"publisher","award":["Department of Navy Grant N629092412119"],"award-info":[{"award-number":["Department of Navy Grant N629092412119"]}],"id":[{"id":"10.13039\/100000006","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:p>We analyze excitation and relaxation dynamics in a two-dimensional heterogeneous excitable medium described by a smoothly regularized three-variable Fenton\u2013Karma model. To relate spatial heterogeneity to a global observable, we examine the dipole response together with the evolution of two activation-threshold manifolds associated with distinct regimes of the excitation\u2013relaxation dynamics of the model. We show that increasing diffusion contrast does not produce a monotonic change in the global excitation\u2013relaxation organization. For weak contrast, excitation remains globally connected despite deformation of the excitation pattern. For intermediate contrast, the system fails to establish a globally connected excited state outside the heterogeneous region, leading to the disappearance of the characteristic negative T-wave-like minimum in the dipole signal. However, a further increase in diffusion contrast restores global connectivity despite the persistence of a trapped low-potential region within the heterogeneity. These results demonstrate that localized heterogeneity can induce a nonmonotonic reorganization of excitation\u2013relaxation dynamics by modifying the ability of the system to establish globally connected excitation. Simultaneously, the global dipole signal directly encodes transitions between regimes with and without a globally connected excited state.<\/jats:p>","DOI":"10.1063\/5.0348139","type":"journal-article","created":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T17:54:24Z","timestamp":1788285264000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Nonmonotonic reorganization of excitation and relaxation in multidimensional excitable media"],"prefix":"10.1063","volume":"36","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6728-8868","authenticated-orcid":false,"given":"Slobodanka","family":"Galovic","sequence":"first","affiliation":[{"name":"Vinca Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, 1 Belgrade,","place":["Serbia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4031-6870","authenticated-orcid":false,"given":"Zoran","family":"Ivic","sequence":"additional","affiliation":[{"name":"Vinca Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, 1 Belgrade,","place":["Serbia"]},{"name":"Department of Physics, Institute of Theoretical and Computational Physics, University of Crete 2 , Heraclion,","place":["Greece"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7688-3792","authenticated-orcid":false,"given":"Dalibor","family":"Chevizovich","sequence":"additional","affiliation":[{"name":"Vinca Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, 1 Belgrade,","place":["Serbia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4793-0224","authenticated-orcid":false,"given":"Giorgos P.","family":"Tsironis","sequence":"additional","affiliation":[{"name":"Department of Physics, Institute of Theoretical and Computational Physics, University of Crete 2 , Heraclion,","place":["Greece"]},{"name":"John A. Paulson School of Engineering and Applied Sciences, Harvard University 3 , Cambridge, Massachusetts 02138,","place":["USA"]},{"name":"4 Faculty of Engineering, Tashkent University of Technology, Tashkent 100095, Uzbekistan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"317","published-online":{"date-parts":[[2026,9,1]]},"reference":[{"key":"2026090208512370100_c1","volume-title":"Mathematical Physiology","year":"2009"},{"key":"2026090208512370100_c2","volume-title":"The Geometry of Biological Time","year":"2001"},{"key":"2026090208512370100_c3","doi-asserted-by":"publisher","first-page":"61","DOI":"10.1016\/0167-2789(91)90194-E","article-title":"A model for fast computer simulation of waves in excitable media","volume":"49","year":"1991","journal-title":"Phys. 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