Indeed, neuroimaging cognitive processes in young and older adults has literally changed our understanding of the aging mind. It has been known for decades that, as cognitive tasks become more complex, performance between old and young adults

becomes increasingly divergent, but speculation about, this finding typically focused on speed of processing as the underlying mechanism.4 One sentient study on interhemispheric connectivity by Reuter-Lorenz et al87 provided behavioral evidence that the use Inhibitors,research,lifescience,medical of two hemispheres to perform a letter-matching task was facilitative for old, but not young. More behavioral studies of this type that focus on linking the recent, neural findings to behavioral phenomena are clearly warranted. There are a number of issues that, arise in interpreting Inhibitors,research,lifescience,medical the different, patterns of brain recruitment between old and young. We do not, know whether the different,

forms of dedifferentiation observed in older subjects are compensatory and adaptive, suggesting successful aging, or are a harbinger of neuropathological changes (although there are certainly hints that, they are compensatory, see ZVADFMK Cabeza48 for a summary). We cannot be sure whether the different patterns reflect strategy Inhibitors,research,lifescience,medical differences or functional differences. We do not actually know what young adults are doing with the unrecruited

areas activated only by the old. Do young adults have cognitive reserves that they may Inhibitors,research,lifescience,medical draw upon when they are ill or stressed, evidencing recruitment, patterns like older adults? We do not understand the role of the environment, nutrition, and toxic Inhibitors,research,lifescience,medical substances in altering neurodevelopmental trajectories that may result, in dedifferentiation. Despite the many unresolved questions as well as problems associated with interpretation of findings, a corpus of work is emerging that, strongly suggests that older adults recruit more symmetrically from the two hemispheres than young adults in frontal areas to perform a range of cognitive tasks. little is known about recruitment patterns in other areas of the brain and this is another important new frontier. Given the infancy of the field, we know quite a lot and there is little question that neural findings are Cediranib (AZD2171) changing the way we think about the behavioral aspects of cognitive aging. Again, to better understand the phenomena of dedifferentiation, large studies, across multiple laboratories, with standardized imaging protocols, life span samples, extensive behavioral testing, and demographic and medical information appear to be the only way to answer many of the questions about brain-behavior relationships in aging.