The effects of posterior parietal and posterior temporal cortical lesions on multimodal spatial and nonspatial competencies in rats.

The functional consequences of posterior parietal (PPC) and posterior temporal (Te2/3) cortical lesions on rat spatial and nonspatial multimodal learning, and memory were assessed using three behavioral paradigms. In the first, a stimulus-elicited object-place recognition task, PPC-lesioned animals were found to habituate to repeated presentation and dishabituate to changes in the visual and auditory properties of the objects but they fail to respond to changes in their location. The Te2/3-lesioned animals recognized changes in spatial location, but not changes in auditory or visual characteristics of the objects. Sham controls recognized both. In water maze-based auditory and visual place object conditional learning tasks, Te2/3 and Sham controls learned both discriminations, whereas the performance of PPC animals was significantly retarded. In the third paradigm, all three groups learned the visual discriminations. Although PPC-lesioned animals subsequently demonstrated recognition of the amodal property of duration in a visual/auditory cross-modal transfer (CMT) test, they were unable to do so on two CMT tasks involving the property of space. In all three tests, the Sham controls consistently displayed CMT and the Te2/3-lesioned animals did not. The present study extends the description of somewhat distinctive roles played by two association cortical regions (PPC and Te2/3) in the perceptual/cognitive functioning, particularly with respect to auditory stimuli and correspondences between auditory and visual events.