Effects of hippocampal and parietal cortex lesions on the processing of multiple-object scenes

Rats were taught 1 of 3 types of multiple-object scene discrimination. Manipulations included either replacing (object based), displacing (space based), or replacing and displacing (object/space based) 1 object in the scene. Once trained, rats received hippocampal, parietal cortex, or cortical control lesions and then were retested. Parietal cortex-and hippocampal-lesioned rats displayed deficits on both the space and object/space tasks but not the object task. The hippocampal-lesioned group's deficit on the object/space task was only transient, whereas the impairments of the parietal cortex-lesioned rats were stable for both tasks. The parietal cortex-lesioned rats sustained difficulty with the object/space task may indicate an inability to switch cognitive strategies.