Age-related Changes in the Structure and Dynamics of the Semantic Network.

Normal aging has variable effects on language comprehension, perhaps because comprehension mechanisms vary in their dependence on network structure versus network dynamics. To test claims that processing dynamics are more affected by age than structure, we used EEG to measure and compare the impact of neighborhood size, a core measure of the structure of the lexico-semantic network, and repetition, a simple measure of processing dynamics, on single word processing. Older adults showed robust effects of neighborhood size on the N400, comparable to those elicited by young adults, but reduced effects of repetition. Furthermore, older adults with greater verbal fluency, print exposure, and reading comprehension showed greater repetition effects, suggesting some older adults can maintain processing dynamics that are similar to those of young adults. Thus, the organizational structure of the semantic network seems stable across normal aging, but (some) older adults may struggle to adjust activation states within that network.