Figure 3.

Differences in acquisition of a spatial reference memory during training distributed across several days. The graph illustrates the distance to find the hidden platform during training trials each day for middle-aged (gray circles), and young (open circles) animals. Older animals may exhibit an initial saw-tooth pattern of performance across days (dashed lines) suggesting increased forgetting. However, this group is able to acquire a spatial reference memory over the course of training and is, therefore, classified as aged unimpaired (filled circles). In contrast, a subgroup of aged animals may exhibit profound learning deficits such that they are unable to acquire a spatial reference memory with repeated training to the same location (filled triangles).