THE EFFECTS OF PARIETAL CORTEX LESIONS ON AN OBJECT SPATIAL LOCATION PAIRED-ASSOCIATE TASK IN RATS

The present experiment was conducted in order to test the hypotheses ( 1) that the posterior parietal cortex (PPC) serves as a neural system that is critical for binding spatial location and object information i n long-term memory and (2) that even restricted lesions of the PPC wou ld result in similar deficits. Long-Evans rats were given either a lar ge or a small PPC lesion or a control surgery under Nembutal anesthesi a. After a 1-week recovery period, the rats were tested on either an o bject or a spatial location go/no-go successive discrimination task. A fter reaching criterion (a minimum of a 5 sec difference between rewar d and nonreward trials), they were trained on the other discrimination . After reaching criterion on the second discrimination, all of the ra ts were trained on a successive discrimination go/no-go task in which they had to remember which object/spatial location pairs had been asso ciated with reward. As compared with controls, neither the small nor t he large PPC lesion impaired object or spatial location discrimination . In the paired-associate object/spatial location task, both large and small PPC lesioned rats were impaired, relative to controls. These da ta suggest that the rodent PPC is not involved in object or spatial lo cation discrimination but rather is involved in discrimination and lon g-term memory for the combination of object and spatial location infor mation.