Context-dependent sensory processing within the predictive coding framework relies on detecting mismatches between incoming stimuli and internal predictive models. Sensory deviants elicit prediction errors, seen as enhanced neural responses, that update these models and influence attention and behavior. Although prediction errors have been widely observed across the brain, the downstream processes that link them to attentional shifts and decision-making remain poorly understood. In this study, we recorded electrocorticography in urethane-anesthetized rats and identified robust cortical slow oscillations, characterized by reliable transitions between Up and Down states. Deviant stimuli in an auditory oddball paradigm evoked an initial prediction error, followed by prolonged, all-or-nothing cortical Up states whose occurrence depended on anesthetic depth. These results indicate that, under anesthesia, sensory deviants trigger cortical state transitions, suggesting that in wakefulness, such shifts may support attentional reorientation and behavioral decision-making.