Functional connectivity in resting-state fMRI (rs-fMRI) in opioid use disorder Neli Atanasova, Anna Todeva-Radneva, Kristina Stoyanova, Elena Psederska, Drozdstoy Stoyanov, Nikoleta Traykova and Jasmin Vassileva Eur. Phys. J. Spec. Top., Publication ahead of print Published online: 25 March 2025 DOI: 10.1140/epjs/s11734-025-01591-2