Dissociation of learning and performance deficits in aged mice

The present study was undertaken to determine whether an age-related learning deficit would occur in a complex visual discrimination task and whether the learning impairment could be separated from performance deficits. The study also sought to determine whether treatment with an inhibitor of protein synthesis, anisomycin, would impair learning in this task. Two age groups (7-10 mo; 27-30 mo) of C56BL/6j mice were given training in a five-choice, simultaneous, visual discrimination task. Errors, freezing, avoidances, and response latencies were recorded. Results revealed that the difference in errors between the two groups disappeared during the middle part of training whereas the difference in the performance measures persisted until the end of training. Anisomycin caused increased errors in the adult but not the old mice. These results indicate that old mice can learn a discrimination task as well as adults but the rate of learning is slower, whereas their physical performance on the task is persistently inferior to adult mice.