A reversible rat model of hyposmia affects respiration-linked brain oscillations and behavior.

Rhythmic breathing coordinates neural activity across olfactory and limbic circuits by coupling nasal airflow to oscillations in the olfactory bulb (OB) and downstream networks. To test how reduced peripheral olfactory input reshapes this respiration-linked coordination, we developed a reversible hyposmia model in rats using intranasal gadolinium chloride. This manipulation impaired hidden cookie performance for around 1 week and was accompanied by nasal epithelial damage. Hyposmia robustly decreased OB respiration-linked (1-10 Hz) and gamma (30-90 Hz) power, with smaller reductions in prefrontal cortex and ventral striatum. In the OB, oscillatory changes were confined to wakefulness, while slow-wave sleep activity was largely preserved, consistent with intact top-down drive during sleep. Additionally, hyposmia increased anxiety-like behavior and produced minor changes in recognition memory without altering locomotion or hedonic drive. Together, these findings connect peripheral nasal function to state-dependent brain synchrony and affect-related behavior.