Neural mechanisms of age-related changes in language performance: A pilot fNIRS study

Healthy aging is associated with changes in neural organization that may influence language production. Using task-based fNIRS, we examined cortical activation and functional connectivity during overt picture naming and sentence repetition in Mandarin speakers. Seventeen right-handed adults (10 younger, mean age = 22.1; 7 older, mean age = 58.6) completed both tasks while HbO responses were recorded over fronto-temporo-parietal cortex. Block-averaged HbO activation did not differ reliably between groups in either task. In contrast, the primary task-epoch connectivity analysis indicated stronger dorsolateral prefrontal-temporo-parietal coupling in older adults during picture naming; however, this group difference was not statistically robust in a more conservative baseline-referenced contrast. No connections survived correction for multiple comparisons during sentence repetition. These results suggest that, under relatively low-demand overt speech production, age-related differences may be more evident in network-level interactions than in mean regional activation magnitude. Task-based fNIRS may be useful for probing age-related modulation of speech-related brain networks during overt language production.