Perseverative instrumental and Pavlovian responding to conditioned stimuli in serotonin transporter knockout rats

► Effects of Pavlovian conditioned stimuli on instrumental behavior were studied. ► Serotonin transporter knockout rats were compared with wild-type counterparts. ► Transporter knockout resulted in perseverative responding to Pavlovian stimuli. ► Perseveration was associated with altered reactivity in corticolimbic circuitries.