Posterior parietal cortex lesions severely disrupt spatial learning in DBA mice characterized by a genetic hippocampal dysfunction

C57BL/6 (C57) and DBA/2 (DBA) inbred mice with posterior parietal cortex or sham lesions were tested in a radial eight-arm maze task with all the paths baited. In the high learner C57 strain, parietal lesions produced a limited impairment of performance without affecting maze-running strategies while the same lesions were found to affect more severely performance in the poor learner DBA strain. Because (1) the processing of spatial information has been found to depend on the conjunctive participation of the hippocampus and the posterior parietal cortex, and (2) DBA mice represent a genetic model of hippocampal dysfunction, the fact that parietal lesions impair spatial performance more severely in the DBA strain suggests that the contribution of the posterior parietal cortex to spatial learning depends on the degree of functionality of the hippocampus.