Age-dependent impairment of delay and trace eyeblink conditioning in mice.

The age effect on classical eyeblink conditioning in unrestrained mice (C57BL/6J strain) was evaluated. Mice were trained at one of three age periods (8, 45-50 or 85-90 weeks). In the delay paradigm, significant learning deficits were evident in the 85-90 week-old group, but no deficits were observed in the behavior of the 45-50 week-old group. On the other hand, in the trace paradigm with a stimulus-free trace interval of 500 ms, significant deficits became apparent at the age of 45-50 weeks. These results indicate that trace eyeblink conditioning is more susceptible to age-related deterioration of memory in mice than delay eyeblink conditioning.