There were large age differences, however, observed between age groups in wayfinding. Additionally, structural magnetic resonance imaging (MRI) scans were performed on the older subjects, and volumes of the hippocampus, caudate and prefrontal cortex were obtained. There were no significant associations between prefrontal cortex volume and navigation performance, but there were associations with the other two structures examined. The volume of the hippocampus (but not caudate; Fig. 1C) was associated with wayfinding accuracy; those older individuals with the largest hippocampi showed the shortest distances to find
the landmark (Fig. 1A). The volume of the caudate (not hippocampus; Fig. 1B), on the other hand, was associated with accuracy in the route learning task; the older individuals with the largest caudate volume also exhibited the most
selleck accurate routes (Fig. 1D). While this study did not explicitly examine whether the difficulty that older adults have in the use of cognitive maps is in their formation or their use, data from Iaria et al. (2009) suggest that older adults take longer to form effective maps and also use them less accurately once acquired. While there are many more demonstrations that behaviors dependent on the hippocampus are altered in aging, those described above illustrate one consistent cognitive change that is observed across species boundaries, namely Veliparib purchase impaired wayfinding. This consistent observation provides an opportunity to examine these behaviors in
relation to the neurobiological changes that may be responsible Cyclic nucleotide phosphodiesterase for this cognitive outcome. One possible contribution to age-related declines on hippocampus-dependent tests was mentioned in the previous section: change in volume. While noninvasive imaging methods have great power to assess brains in the absence of potential histological artifacts, the reasons for the volume changes cannot be specified at the resolution of these methods, and additional cell and synapse counts and morphological analyses are required. Nonetheless, various MRI techniques can be used across species to help dissect changes due to aging vs. those of prodromal disease. Because the full pathological syndrome known as Alzheimer’s disease (AD) only occurs spontaneously in humans, animal models that age but do not exhibit AD are helpful guides for understanding and separating what is normal from what is pathological. Not surprisingly, in the human cognitive aging literature there are reports of hippocampal atrophy across age (e.g., O’Brien et al., 1997; Tisserand et al., 2000; Raz et al., 2004, 2010), along with reports of stability of overall hippocampal volume during aging (e.g., Van Petten, 2004; Sullivan et al., 2005).