Age-related effects on eyeblink conditioning in the F344 x BN F1 hybrid rat.

Young, middle-aged, old, and senescent Fischer 344 x Brown Norway F1 hybrid rats were trained in either the trace or delay eyeblink conditioning task in order to investigate how aging affects associative learning and memory over the life span. Senescent rats at 34-35 months showed severe impairments in acquisition of the trace task with a 250 msec trace interval, which is hippocampally-dependent, and were mildly impaired in the simple delay eyeblink conditioning task. Middle aged animals, varying in age from 18-24 months, acquired the trace and delay eyeblink paradigms as well as young rats (6 months). However, at 28-29 months, approximately 50% of the old animals showed impairments in the trace 250 msec eyeblink task. Our results show that trace eyeblink conditioning is an age-sensitive task useful for studying the neural substrates underlying associative learning and memory in rats, as has been previously shown in humans and rabbits.