AGE AND EXPERIENCE-DEPENDENT REPRESENTATIONAL REORGANIZATION DURING SPATIAL-LEARNING

Previously, we found that aged rats showed a significant enhancement o r hippocampal CA1 place cell spatial specificity, as well as a reducti on of hilar place cell spatial specificity, during asymptote performan ce of a spatial memory task. Because such an age effect was not observ ed when animals performed a nonspatial task, the present study tested the hypothesis that the different patterns of spatial selectivity obse rved in memory and nonmemory tests reflected a redistribution of spati al representations that occurred in response to changing task demands. In the present experiment, after animals became familiar with the tes t environment and motor demands of performance on a radial maze, CA1 a nd hilar place cells were recorded as they learned a spatial memory ta sk. CA1 place cells recorded from unimpaired old, but not impaired old or young, animals became more spatially selective as animals learned the task. Hilar spatial selectivity for both apr groups was not signif icantly related to choice accuracy. These data support the hypothesis that at least a subpopulation of aged rats may benefit from reorganiza tion of spatial representations in such a way that the normal age-rela ted spatial learning deficit is attenuated. (C) 1997 Elsevier Science Inc.