Electroencephalographic coherence, aging, and memory: distinct responses to background context and stimulus repetition in younger, older, and older declined groups.

The current study examines the EEG coherence of young, old, and old declined adults performing a visual paired-associates task. In order to examine the effects of encoding context and stimulus repetition, target pairs were presented on either detailed or white backgrounds and were repeatedly presented during both early and late phases of encoding. Younger adults were found to have lower levels of frontal-temporal and temporal-parietal coherence, but higher levels of frontal-parietal coherence, particularly for the gamma frequency band. A number of differential coherence responses to background context and early- versus late-encoding phases were also observed across the groups, particularly for lower alpha and upper alpha frequencies. Coherence-performance maps were generated to further explore topographical differences in the relationship between coherence and performance across groups. Results revealed a more diffuse pattern of negative coherence-performance relations in older declined adults. Results are discussed in light of the literature on age-related cognitive decline.