An age comparison of the rates of acquisition and forgetting of spatial information in relation to long-term enhancement of hippocampal synapses.

Age differences in the rates of acquisition and forgetting of a spatial memory problem were compared with corresponding differences in the rates of increase and decay of long-term synaptic enhancement (LTE) of hippocampal synapses, induced by high-frequency stimulation of perforant path fibers. Old animals approached their final asymptotic performance levels more slowly than did the young animals and exhibited faster rates of forgetting of the problem. Similarly, LTE reached its maximum more slowly in the old animals and decayed more quickly. Although the absolute rates of behavioral acquisition and forgetting were different from the corresponding rates of increase and decay of LTE, the relative differences between age groups were rather similar. This was particularly true for the comparison of forgetting with LTE decay. The relation of these data to the hypothesis that LTE underlies spatial learning and memory is discussed.