Cerebral embolization leads to memory impairment of several learning tasks in rats

The effects of cerebral embolization, produced by injecting microspheres into the left internal carotid artery, on passive and active avoidance tasks and water filled multiple T-maze task, were studied in male Wistar rats. The rats with cerebral embolization were markedly impaired acquisition and retention of the one-trial passive avoidance response. The impairment depended on the number of microspheres injected and continued for 2 weeks. The cerebral embolized rats were also impaired acquisition of two-way active avoidance response in a shuttle box. These impairments are not due to decrease in shock sensitivity, because there was no significant change in the flinch-jump threshold. The embolized rats also exhibited a significant disturbance in performance of water filled multiple T-maze learning. These results suggest that rats with cerebral embolization are impaired in three different types of learning tasks, and may be useful as an animal model for the vascular type of dementia.