According to prominent theories of aging, the brain may reorganize to compensate for neural deterioration and prevent or offset cognitive decline. A frequent and striking finding in functional imaging studies is that older adults recruit additional regions relative to young adults performing the same task. This is often interpreted as evidence for functional reorganization, suggesting that, as people age, different regions or networks may support the same cognitive functions. Associations between additional recruitment and better performance in older adults have led to the suggestion that the additional recruitment may contribute to preserved cognitive function in old age and may explain some of the variation among individuals in preservation of function. However, many alternative explanations are possible, and recent findings and methodological developments have highlighted the need for more systematic approaches to determine whether reorganization occurs with age and whether it benefits performance. We reevaluate current evidence for compensatory functional reorganization in the light of recent moves to address these challenges.

This study used event-related fMRI to examine the impact of the adoption of different retrieval orientations on the neural correlates of recollection. In each of two study–test blocks, participants encoded a mixed list of words and pictures and then performed a recognition memory task with words as the test items. In one block, the requirement was to respond positively to test items corresponding to studied words and to reject both new items and items corresponding to the studied pictures. In the other block, positive responses were made to test items corresponding to pictures, and items corresponding to words were classified along with the new items. On the basis of previous ERP findings, we predicted that in the word task, recollection-related effects would be found for target information only. This prediction was fulfilled. In both tasks, targets elicited the characteristic pattern of recollection-related activity. By contrast, nontargets elicited this pattern in the picture task, but not in the word task. Importantly, the left angular gyrus was among the regions demonstrating this dissociation of nontarget recollection effects according to retrieval orientation. The findings for the angular gyrus parallel prior findings for the “left-parietal” ERP old/new effect and add to the evidence that the effect reflects recollection-related neural activity originating in left ventral parietal cortex. Thus, the results converge with the previous ERP findings to suggest that the processing of retrieval cues can be constrained to prevent the retrieval of goal-irrelevant information.

ERPs elicited by correctly classified unstudied items in tests of yes/no recognition memory were used to investigate the neural correlates of retrieval cue processing. Items in Experiment 1 consisted of pictures and their corresponding names, allowing study and test material to be factorially crossed in four separate study–test cycles. The ERPs elicited by unstudied pictures and words were, in each case, more negative-going when the study material belonged to the alternative rather than the same class of items. These findings demonstrate that previously reported ERP “retrieval orientation effects” depend on differences in similarity between study and test items, and not on the form of the sought for material. In Experiments 2a and 2b, study materials were auditory words and pictures, and the test items were visual words. In both experiments, ERPs elicited by unstudied test words were more negative-going when pictures rather than auditory words were the study material. Thus, ERP retrieval orientation effects do not depend on the employment of a copy cue condition. It is proposed that the effects reflect differences in the processing necessary to maximize over lap between cue and memory representations.