Spatial learning impairments in aged rats trained with a salient configuration of stimuli

Aged animals are impaired in many maze learning tasks, suggesting that they may have a spatial learning deficit. Alternatively, declining sensory/perceptual faculties in aged animals may impede their ability to use complex arrangements of Stimuli that are necessary for spatial learning. To test this possibility, we conducted place learning in the Morris water maze in the presence of a very simple and salient configuration of Stimuli that consisted of a black plexiglass sheet, subtending an arc of 110° around the inside wall of the water maze. In Experiment 1, place learning in young rats was guided by this configuration of Stimuli. In Experiment 2, a prominent place-learning deficit in aged rats was observed when animals were trained with this configuration. Thus, the place-learning impairment in aged animals may not be confined to perceptual deficits that decrease an animal’s ability to use complex configurations of stimuli.