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. Author manuscript; available in PMC: 2010 Apr 1.
Published in final edited form as: Neurobiol Aging. 2007 Sep 21;30(4):646–655. doi: 10.1016/j.neurobiolaging.2007.08.004

Fig. 3. Frequency Histograms of Individual Probe Trial Performance in the Spatial Reference Memory Task for Young and Aged 344 Rats.

Fig. 3

Frequency distributions of performance on individual probe trials for young (A, C) and aged (B,D) rats are shown for probe trials early in training (probe trials 1 and 2 (A.,B.)) and late in training (probe trials 3 and 4 (C.,D.)). Both age groups show improved performance over the course of training as indicated by a leftward shift in the distribution between probe trials 1&2 and 3&4. Note that unlike training trials, in which individual trial length can be confounded by non-mnemonic variables (e.g. circling strategy and start position), only unimodal distributions are observed across ages in the probe trial analysis. These data strongly support the contention that cognitive performance is consistent across trials, even at advanced age.