Reduced Specificity of Hippocampal and Posterior Ventrolateral Prefrontal Activity during Relational Retrieval in Normal Aging
Young and older adults (elderly in Experiment 1 and middle-aged in Experiment 2) received successive sentence recall tasks for which one-half of the sentences were read in a male voice and one-half in a female voice. With regard to the sex of voice component, the first task was administered under incidental learning conditions and the second under intentional learning conditions. With regard to sentence content, both tasks were administered under intentional learning conditions. The results indicated that encoding voice information is a cognitively effortful, age sensitive process. For older adults, both elderly and middle-aged, enhanced voice encoding under the intentional condition, relative to the incidental condition, was accompanied by a significant decrement in sentence recall. For young adults, the trade off effect was not large enough to reach statistical significance. The age difference apparently reflects the diminished processing capacity of older adults relative to young adults, with the decrease in capacity having its onset by middle age.